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Cutts A, Chowdhury S, Ratkay LG, Eyers M, Young C, Namdari R, Cadieux JA, Chahal N, Grimwood M, Zhang Z, Lin S, Tietjen I, Xie Z, Robinette L, Sojo L, Waldbrook M, Hayden M, Mansour T, Pimstone S, Goldberg YP, Webb M, Cohen CJ. Potent, Gut-Restricted Inhibitors of Divalent Metal Transporter 1: Preclinical Efficacy against Iron Overload and Safety Evaluation. J Pharmacol Exp Ther 2023; 386:4-14. [PMID: 36958846 DOI: 10.1124/jpet.122.001435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 01/26/2023] [Accepted: 02/21/2023] [Indexed: 03/25/2023] Open
Abstract
Divalent metal transporter 1 (DMT1) cotransports ferrous iron and protons and is the primary mechanism for uptake of nonheme iron by enterocytes. Inhibitors are potentially useful as therapeutic agents to treat iron overload disorders such as hereditary hemochromatosis or β-thalassemia intermedia, provided that inhibition can be restricted to the duodenum. We used a calcein quench assay to identify human DMT1 inhibitors. Dimeric compounds were made to generate more potent compounds with low systemic exposure. Direct block of DMT1 was confirmed by voltage clamp measurements. The lead compound, XEN602, strongly inhibits dietary nonheme iron uptake in both rats and pigs yet has negligible systemic exposure. Efficacy is maintained for >2 weeks in a rat subchronic dosing assay. Doses that lowered iron content in the spleen and liver by >50% had no effect on the tissue content of other divalent cations except for cobalt. XEN602 represents a powerful pharmacological tool for understanding the physiologic function of DMT1 in the gut. SIGNIFICANCE STATEMENT: This report introduces methodology to develop potent, gut-restricted inhibitors of divalent metal transporter 1 (DMT1) and identifies XEN602 as a suitable compound for in vivo studies. We also report novel animal models to quantify the inhibition of dietary uptake of iron in both rodents and pigs. This research shows that inhibition of DMT1 is a promising means to treat iron overload disorders.
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Affiliation(s)
- Alison Cutts
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Sultan Chowdhury
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Laszlo G Ratkay
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Maryanne Eyers
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Clint Young
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Rostam Namdari
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Jay A Cadieux
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Navjot Chahal
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Michael Grimwood
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Zaihui Zhang
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Sophia Lin
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Ian Tietjen
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Zhiwei Xie
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Lee Robinette
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Luis Sojo
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Matthew Waldbrook
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Michael Hayden
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Tarek Mansour
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Simon Pimstone
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Y Paul Goldberg
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Michael Webb
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
| | - Charles J Cohen
- Xenon Pharmaceuticals Inc., Burnaby, British Columbia, Canada(A.C., S.C., L.G.R., M.E., C.Y., R.N., J.A.C., N.C., M.G., Z.Z., S.L., I.T., Z.X., L.R., L.S., M.W., M.H., T.M., S.P., Y.P.G., M.W., C.J.C.) and Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada (S.P.)
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Markussen KH, Macedo JKA, Machío M, Dolce A, Goldberg YP, Vander Kooi CW, Gentry MS. The 6th International Lafora Epilepsy Workshop: Advances in the search for a cure. Epilepsy Behav 2021; 119:107975. [PMID: 33946009 PMCID: PMC8154720 DOI: 10.1016/j.yebeh.2021.107975] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 04/01/2021] [Indexed: 10/21/2022]
Abstract
Lafora disease (LD) is a fatal childhood dementia with severe epilepsy and also a glycogen storage disease that is caused by recessive mutations in either the EPM2A or EPM2B genes. Aberrant, cytoplasmic carbohydrate aggregates called Lafora bodies (LBs) are both a hallmark and driver of the disease. The 6th International Lafora Epilepsy Workshop was held online due to the pandemic. Nearly 300 clinicians, academic and industry scientists, trainees, NIH representatives, and LD friends and family members participated in the event. Speakers covered aspects of LD including progress towards the clinic, the importance of establishing clinical progression, translational progress with repurposed drugs and additional pre-clinical therapies, and novel discoveries that define foundational LD mechanisms.
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Affiliation(s)
- Kia H. Markussen
- Department of Molecular and Cellular Biochemistry, Epilepsy and Brain Metabolism Alliance, and Epilepsy Research Center, University of Kentucky College of Medicine, Lexington, Kentucky 40536, USA
| | - Jessica K. A. Macedo
- Department of Molecular and Cellular Biochemistry, Epilepsy and Brain Metabolism Alliance, and Epilepsy Research Center, University of Kentucky College of Medicine, Lexington, Kentucky 40536, USA,Markey Cancer Center, University of Kentucky, Lexington, Kentucky, USA
| | - María Machío
- Fundación Jimenez Diaz Hospital, UAM, 28045 Madrid, Spain
| | - Alison Dolce
- Division of Neurology, Department of Pediatrics, University of Texas-Southwestern, Dallas, Texas 75390, USA
| | - Y. Paul Goldberg
- Department of Clinical Development, Ionis Pharmaceuticals, Carlsbad, CA, 92008 USA
| | - Craig W. Vander Kooi
- Department of Molecular and Cellular Biochemistry, Epilepsy and Brain Metabolism Alliance, and Epilepsy Research Center, University of Kentucky College of Medicine, Lexington, Kentucky 40536, USA,Lafora Epilepsy Cure Initiative (LECI), USA
| | - Matthew S. Gentry
- Department of Molecular and Cellular Biochemistry, Epilepsy and Brain Metabolism Alliance, and Epilepsy Research Center, University of Kentucky College of Medicine, Lexington, Kentucky 40536, USA,Lafora Epilepsy Cure Initiative (LECI), USA
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Gentry MS, Afawi Z, Armstrong DD, Delgado-Escueta A, Goldberg YP, Grossman TR, Guinovart JJ, Harris F, Hurley TD, Michelucci R, Minassian BA, Sanz P, Worby CA, Serratosa JM. The 5th International Lafora Epilepsy Workshop: Basic science elucidating therapeutic options and preparing for therapies in the clinic. Epilepsy Behav 2020; 103:106839. [PMID: 31932179 PMCID: PMC7024738 DOI: 10.1016/j.yebeh.2019.106839] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 12/03/2019] [Accepted: 12/03/2019] [Indexed: 12/19/2022]
Abstract
Lafora disease (LD) is both a fatal childhood epilepsy and a glycogen storage disease caused by recessive mutations in either the Epilepsy progressive myoclonus 2A (EPM2A) or EPM2B genes. Hallmarks of LD are aberrant, cytoplasmic carbohydrate aggregates called Lafora bodies (LBs) that are a disease driver. The 5th International Lafora Epilepsy Workshop was recently held in Alcala de Henares, Spain. The workshop brought together nearly 100 clinicians, academic and industry scientists, trainees, National Institutes of Health (NIH) representation, and friends and family members of patients with LD. The workshop covered aspects of LD ranging from defining basic scientific mechanisms to elucidating a LD therapy or cure and a recently launched LD natural history study.
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Affiliation(s)
- Matthew S. Gentry
- Department of Molecular and Cellular Biochemistry, Epilepsy and Brain Metabolism Alliance, and Epilepsy Research Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA,Lafora Epilepsy Cure Initiative (LECI), USA,Corresponding author at: 741 S. Limestone, BBSRB, Room 177, Lexington, KY 40536, USA., (M.S. Gentry)
| | - Zaid Afawi
- Sackler School of Medicine, Tel-Aviv University, Ramat Aviv, Israel,Department of Psychiatry, Erasmus University Medical Center, Rotterdam, the Netherlands
| | | | - Antonio Delgado-Escueta
- Lafora Epilepsy Cure Initiative (LECI), USA,Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
| | | | | | - Joan J. Guinovart
- Lafora Epilepsy Cure Initiative (LECI), USA,Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology, 08028 Barcelona, Spain,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Frank Harris
- Lafora Epilepsy Cure Initiative (LECI), USA,Chelsea’s Hope, PO Box 348626, Sacramento, CA 95834, USA
| | - Thomas D. Hurley
- Lafora Epilepsy Cure Initiative (LECI), USA,Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Roberto Michelucci
- Lafora Epilepsy Cure Initiative (LECI), USA,IRCCS-Istituto delle Scienze Neurologiche di Bologna, Unit of Neurology, Bellaria Hospital, Bologna, Italy
| | - Berge A. Minassian
- Lafora Epilepsy Cure Initiative (LECI), USA,Department of Pediatrics, University of Texas Southwestern, Dallas, TX 75390, USA
| | - Pascual Sanz
- Lafora Epilepsy Cure Initiative (LECI), USA,Instituto de Biomedicina de Valencia (IBV-CSIC) and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 46010 Valencia, Spain
| | - Carolyn A. Worby
- Lafora Epilepsy Cure Initiative (LECI), USA,Department of Pharmacology, University of California San Diego, La Jolla, CA 92093, USA
| | - Jose M. Serratosa
- Lafora Epilepsy Cure Initiative (LECI), USA,Laboratory of Neurology, IIS-Jimenez Diaz Foundation, UAM, 28045 Madrid, Spain,Biomedical Research Networking Center on Rare Diseases (CIBERER), 28029 Madrid, Spain
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Brewer MK, Grossman TR, McKnight TR, Goldberg YP, Landy H, Gentry MS. The 4th International Lafora Epilepsy Workshop: Shifting paradigms, paths to treatment, and hope for patients. Epilepsy Behav 2019; 90:284-286. [PMID: 30528121 PMCID: PMC6457339 DOI: 10.1016/j.yebeh.2018.11.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 11/15/2018] [Indexed: 10/27/2022]
Affiliation(s)
- M. Kathryn Brewer
- Department of Molecular and Cellular Biochemistry, Epilepsy and Brain Metabolism Alliance, Lafora Epilepsy Cure Initiative, and Epilepsy Research Center, University of Kentucky College of Medicine, Lexington, KY, 40536 USA
| | | | | | | | - Hal Landy
- Valerion Therapeutics, Concord, MA 01742, USA
| | - Matthew S. Gentry
- Department of Molecular and Cellular Biochemistry, Epilepsy and Brain Metabolism Alliance, Lafora Epilepsy Cure Initiative, and Epilepsy Research Center, University of Kentucky College of Medicine, Lexington, KY, 40536 USA,Corresponding author: 741 S. Limestone, BBSRB, Room 177, Lexington, KY 40536; ; 859-323-8482
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Huang J, Vanoye CG, Cutts A, Goldberg YP, Dib-Hajj SD, Cohen CJ, Waxman SG, George AL. Sodium channel NaV1.9 mutations associated with insensitivity to pain dampen neuronal excitability. J Clin Invest 2017; 127:2805-2814. [PMID: 28530638 DOI: 10.1172/jci92373] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 03/23/2017] [Indexed: 02/05/2023] Open
Abstract
Voltage-gated sodium channel (NaV) mutations cause genetic pain disorders that range from severe paroxysmal pain to a congenital inability to sense pain. Previous studies on NaV1.7 and NaV1.8 established clear relationships between perturbations in channel function and divergent clinical phenotypes. By contrast, studies of NaV1.9 mutations have not revealed a clear relationship of channel dysfunction with the associated and contrasting clinical phenotypes. Here, we have elucidated the functional consequences of a NaV1.9 mutation (L1302F) that is associated with insensitivity to pain. We investigated the effects of L1302F and a previously reported mutation (L811P) on neuronal excitability. In transfected heterologous cells, the L1302F mutation caused a large hyperpolarizing shift in the voltage-dependence of activation, leading to substantially enhanced overlap between activation and steady-state inactivation relationships. In transfected small rat dorsal root ganglion neurons, expression of L1302F and L811P evoked large depolarizations of the resting membrane potential and impaired action potential generation. Therefore, our findings implicate a cellular loss of function as the basis for impaired pain sensation. We further demonstrated that a U-shaped relationship between the resting potential and the neuronal action potential threshold explains why NaV1.9 mutations that evoke small degrees of membrane depolarization cause hyperexcitability and familial episodic pain disorder or painful neuropathy, while mutations evoking larger membrane depolarizations cause hypoexcitability and insensitivity to pain.
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Affiliation(s)
- Jianying Huang
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine; and Rehabilitation Research Center, Veterans Administration Connecticut Healthcare System, West Haven, Connecticut, USA
| | - Carlos G Vanoye
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Alison Cutts
- Xenon Pharmaceuticals, Burnaby, British Columbia, Canada
| | | | - Sulayman D Dib-Hajj
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine; and Rehabilitation Research Center, Veterans Administration Connecticut Healthcare System, West Haven, Connecticut, USA
| | | | - Stephen G Waxman
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine; and Rehabilitation Research Center, Veterans Administration Connecticut Healthcare System, West Haven, Connecticut, USA
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
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Semaka A, Kay C, Doty C, Collins JA, Bijlsma EK, Richards F, Goldberg YP, Hayden MR. CAG size-specific risk estimates for intermediate allele repeat instability in Huntington disease. J Med Genet 2013; 50:696-703. [PMID: 23896435 DOI: 10.1136/jmedgenet-2013-101796] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION New mutations for Huntington disease (HD) occur due to CAG repeat instability of intermediate alleles (IA). IAs have between 27 and 35 CAG repeats, a range just below the disease threshold of 36 repeats. While they usually do not confer the HD phenotype, IAs are prone to paternal germline CAG repeat instability. Consequently, they may expand into the HD range upon transmission to the next generation, producing a new mutation. Quantified risk estimates for IA repeat instability are extremely limited but needed to inform clinical practice. METHODS Using small-pool PCR of sperm DNA from Caucasian men, we examined the frequency and magnitude of CAG repeat instability across the entire range of intermediate CAG sizes. The CAG size-specific risk estimates generated are based on the largest sample size ever examined, including 30 IAs and 18 198 sperm. RESULTS Our findings demonstrate a significant risk of new mutations. While all intermediate CAG sizes demonstrated repeat expansion into the HD range, alleles with 34 and 35 CAG repeats were associated with the highest risk of a new mutation (2.4% and 21.0%, respectively). IAs with ≥33 CAG repeats showed a dramatic increase in the frequency of instability and a switch towards a preponderance of repeat expansions over contractions. CONCLUSIONS These data provide novel insights into the origins of new mutations for HD. The CAG size-specific risk estimates inform clinical practice and provide accurate risk information for persons who receive an IA predictive test result.
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Affiliation(s)
- Alicia Semaka
- Department of Medical Genetics, Centre for Molecular Medicine & Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada
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Goldberg YP, Pimstone SN, Namdari R, Price N, Cohen C, Sherrington RP, Hayden MR. Human Mendelian pain disorders: a key to discovery and validation of novel analgesics. Clin Genet 2012; 82:367-73. [PMID: 22845492 DOI: 10.1111/j.1399-0004.2012.01942.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 07/03/2012] [Accepted: 07/23/2012] [Indexed: 12/21/2022]
Abstract
We have utilized a novel application of human genetics, illuminating the important role that rare genetic disorders can play in the development of novel drugs that may be of relevance for the treatment of both rare and common diseases. By studying a very rare Mendelian disorder of absent pain perception, congenital indifference to pain, we have defined Nav1.7 (endocded by SCN9A) as a critical and novel target for analgesic development. Strong human validation has emerged with SCN9A gain-of-function mutations causing inherited erythromelalgia (IEM) and paroxysmal extreme pain disorder, both Mendelian disorder of spontaneous or easily evoked pain. Furthermore, variations in the Nav1.7 channel also modulate pain perception in healthy subjects as well as in painful conditions such as osteoarthritis and Parkinson disease. On the basis of this, we have developed a novel compound (XEN402) that exhibits potent, voltage-dependent block of Nav1.7. In a small pilot study, we showed that XEN402 blocks Nav1.7 mediated pain associated with IEM thereby demonstrating the use of rare genetic disorders with mutant target channels as a novel approach to rapid proof-of-concept. Our approach underscores the critical role that human genetics can play by illuminating novel and critical pathways pertinent for drug discovery.
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Affiliation(s)
- Y P Goldberg
- Department of Clinical Development, Xenon Pharmaceuticals Inc, Burnaby, British Columbia, Canada.
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Zhang Z, Kodumuru V, Sviridov S, Liu S, Chafeev M, Chowdhury S, Chakka N, Sun J, Gauthier SJ, Mattice M, Ratkay LG, Kwan R, Thompson J, Cutts AB, Fu J, Kamboj R, Goldberg YP, Cadieux JA. Discovery of benzylisothioureas as potent divalent metal transporter 1 (DMT1) inhibitors. Bioorg Med Chem Lett 2012; 22:5108-13. [DOI: 10.1016/j.bmcl.2012.05.129] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 05/19/2012] [Accepted: 05/29/2012] [Indexed: 01/19/2023]
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Domanski D, Cohen Freue GV, Sojo L, Kuzyk MA, Ratkay L, Parker CE, Goldberg YP, Borchers CH. The use of multiplexed MRM for the discovery of biomarkers to differentiate iron-deficiency anemia from anemia of inflammation. J Proteomics 2012; 75:3514-28. [DOI: 10.1016/j.jprot.2011.11.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 11/18/2011] [Indexed: 10/15/2022]
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10
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Cadieux JA, Zhang Z, Mattice M, Brownlie-Cutts A, Fu J, Ratkay LG, Kwan R, Thompson J, Sanghara J, Zhong J, Goldberg YP. Synthesis and biological evaluation of substituted pyrazoles as blockers of divalent metal transporter 1 (DMT1). Bioorg Med Chem Lett 2011; 22:90-5. [PMID: 22154351 DOI: 10.1016/j.bmcl.2011.11.069] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 11/14/2011] [Accepted: 11/18/2011] [Indexed: 10/15/2022]
Abstract
Three distinct series of substituted pyrazole blockers of divalent metal transporter 1 (DMT1) were elaborated from the high-throughput screening pyrazolone hit 1. Preliminary hit-to-lead efforts revealed a preference for electron-withdrawing substituents in the 4-amido-5-hydroxypyrazole series 6a-l. In turn, this preference was more pronounced in a series of 4-aryl-5-hydroxypyrazoles 8a-j. The representative analogs 6f and 12f were found to be efficacious in a rodent model of acute iron hyperabsorption. These three series represent promising starting points for lead optimization efforts aimed at the discovery of DMT1 blockers as iron overload therapeutics.
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Affiliation(s)
- Jay A Cadieux
- Department of Medicinal Chemistry, Xenon Pharmaceuticals Inc., 3650 Gilmore Way, Burnaby, British Columbia, Canada V5G 4W8.
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11
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Goldberg YP. HotSpots - A new feature in Clinical Genetics. Clin Genet 2008. [DOI: 10.1111/j.1399-0004.1998.tb02570.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Goldberg YP, MacFarlane J, MacDonald ML, Thompson J, Dube MP, Mattice M, Fraser R, Young C, Hossain S, Pape T, Payne B, Radomski C, Donaldson G, Ives E, Cox J, Younghusband HB, Green R, Duff A, Boltshauser E, Grinspan GA, Dimon JH, Sibley BG, Andria G, Toscano E, Kerdraon J, Bowsher D, Pimstone SN, Samuels ME, Sherrington R, Hayden MR. Loss-of-function mutations in the Nav1.7 gene underlie congenital indifference to pain in multiple human populations. Clin Genet 2007; 71:311-9. [PMID: 17470132 DOI: 10.1111/j.1399-0004.2007.00790.x] [Citation(s) in RCA: 342] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Congenital indifference to pain (CIP) is a rare condition in which patients have severely impaired pain perception, but are otherwise essentially normal. We identified and collected DNA from individuals from nine families of seven different nationalities in which the affected individuals meet the diagnostic criteria for CIP. Using homozygosity mapping and haplotype sharing methods, we narrowed the CIP locus to chromosome 2q24-q31, a region known to contain a cluster of voltage-gated sodium channel genes. From these prioritized candidate sodium channels, we identified 10 mutations in the SCN9A gene encoding the sodium channel protein Nav1.7. The mutations completely co-segregated with the disease phenotype, and nine of these SCN9A mutations resulted in truncation and loss-of-function of the Nav1.7 channel. These genetic data further support the evidence that Nav1.7 plays an essential role in mediating pain in humans, and that SCN9A mutations identified in multiple different populations underlie CIP.
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Affiliation(s)
- Y P Goldberg
- Xenon Pharmaceuticals Inc., 3650 Gilmore Way, Burnaby, BC V5G4W8, Canada.
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13
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Bär H, Goudeau B, Wälde S, Casteras-Simon M, Mücke N, Shatunov A, Goldberg YP, Clarke C, Holton JL, Eymard B, Katus HA, Fardeau M, Goldfarb L, Vicart P, Herrmann H. Conspicuous involvement of desmin tail mutations in diverse cardiac and skeletal myopathies. Hum Mutat 2007; 28:374-86. [PMID: 17221859 DOI: 10.1002/humu.20459] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Myofibrillar myopathy (MFM) encompasses a genetically heterogeneous group of human diseases caused by mutations in genes coding for structural proteins of muscle. Mutations in the intermediate filament (IF) protein desmin (DES), a major cytoskeletal component of myocytes, lead to severe forms of "desminopathy," which affects cardiac, skeletal, and smooth muscle. Most mutations described reside in the central alpha-helical rod domain of desmin. Here we report three novel mutations--c.1325C>T (p.T442I), c.1360C>T (p.R454W), and c.1379G>T (p.S460I)--located in desmin's non-alpha-helical carboxy-terminal "tail" domain. We have investigated the impact of these and four--c.1237G>A (p.E413K), c.1346A>C (p.K449T), c.1353C>G (p.I451M), and c.1405G>A (p.V469M)--previously described "tail" mutations on in vitro filament formation and on the generation of ordered cytoskeletal arrays in transfected myoblasts. Although all but two mutants (p.E413K, p.R454W) assembled into IFs in vitro and all except p.E413K were incorporated into IF arrays in transfected C2C12 cells, filament properties differed significantly from wild-type desmin as revealed by viscometric assembly assays. Most notably, when coassembled with wild-type desmin, these mutants revealed a severe disturbance of filament-formation competence and filament-filament interactions, indicating an inherent incompatibility of mutant and wild-type protein to form mixed filaments. The various clinical phenotypes observed may reflect altered interactions of desmin's tail domain with different components of the myoblast cytoskeleton leading to diminished biomechanical properties and/or altered metabolism of the individual myocyte. Our in vitro assembly regimen proved to be a very sensible tool to detect if a particular desmin mutation is able to cause filament abnormalities.
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Affiliation(s)
- Harald Bär
- Department of Cardiology, University of Heidelberg, Heidelberg, Germany
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14
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Abstract
Mutations in a recently identified gene HJV (also called HFE2, or repulsive guidance molecule C, RgmC) are the major cause of juvenile hemochromatosis (JH). The protein product of HJV, hemojuvelin, contains a C-terminal glycosylphosphatidylinositol anchor, suggesting that it can be present in either a soluble or a cell-associated form. Patients with HJV hemochromatosis have low urinary levels of hepcidin, the principal iron-regulatory hormone secreted by the liver. However, neither the specific role of hemojuvelin in maintaining iron homeostasis nor its relationship to hepcidin has been experimentally established. In this study we used hemojuvelin-specific siRNAs to vary hemojuvelin mRNA concentration and showed that cellular hemojuvelin positively regulated hepcidin mRNA expression, independently of the interleukin 6 pathway. We also showed that recombinant soluble hemojuvelin (rs-hemojuvelin) suppressed hepcidin mRNA expression in primary human hepatocytes in a log-linear dose-dependent manner, suggesting binding competition between soluble and cell-associated hemojuvelin. Soluble hemojuvelin was found in human sera at concentrations similar to those required to suppress hepcidin mRNA in vitro. In cells engineered to express hemojuvelin, soluble hemojuvelin release was progressively inhibited by increasing iron concentrations. We propose that soluble and cell-associated hemojuvelin reciprocally regulate hepcidin expression in response to changes in extracellular iron concentration.
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Affiliation(s)
- Lan Lin
- Dept of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1690, USA
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15
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MacDonald MLE, Goldberg YP, Macfarlane J, Samuels ME, Trese MT, Shastry BS. Genetic variants of frizzled-4 gene in familial exudative vitreoretinopathy and advanced retinopathy of prematurity. Clin Genet 2005; 67:363-6. [PMID: 15733276 DOI: 10.1111/j.1399-0004.2005.00408.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Papanikolaou G, Tzilianos M, Christakis JI, Bogdanos D, Tsimirika K, MacFarlane J, Goldberg YP, Sakellaropoulos N, Ganz T, Nemeth E. Hepcidin in iron overload disorders. Blood 2005; 105:4103-5. [PMID: 15671438 PMCID: PMC1895089 DOI: 10.1182/blood-2004-12-4844] [Citation(s) in RCA: 297] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Hepcidin is the principal regulator of iron absorption in humans. The peptide inhibits cellular iron efflux by binding to the iron export channel ferroportin and inducing its internalization and degradation. Either hepcidin deficiency or alterations in its target, ferroportin, would be expected to result in dysregulated iron absorption, tissue maldistribution of iron, and iron overload. Indeed, hepcidin deficiency has been reported in hereditary hemochromatosis and attributed to mutations in HFE, transferrin receptor 2, hemojuvelin, and the hepcidin gene itself. We measured urinary hepcidin in patients with other genetic causes of iron overload. Hepcidin was found to be suppressed in patients with thalassemia syndromes and congenital dyserythropoietic anemia type 1 and was undetectable in patients with juvenile hemochromatosis with HAMP mutations. Of interest, urine hepcidin levels were significantly elevated in 2 patients with hemochromatosis type 4. These findings extend the spectrum of iron disorders with hepcidin deficiency and underscore the critical importance of the hepcidin-ferroportin interaction in iron homeostasis.
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Affiliation(s)
- George Papanikolaou
- First Department of Medicine, National and Kapodistrian University of Athens, Greece
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17
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Delatycki MB, Allen KJ, Gow P, MacFarlane J, Radomski C, Thompson J, Hayden MR, Goldberg YP, Samuels ME. A homozygous HAMP mutation in a multiply consanguineous family with pseudo-dominant juvenile hemochromatosis. Clin Genet 2004; 65:378-83. [PMID: 15099344 DOI: 10.1111/j.0009-9163.2004.00254.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Juvenile hemochromatosis (JH) is an autosomal recessive condition that leads to significant morbidity due to early onset systemic iron overload. The majority of families with JH link to chromosome 1q and were recently found to have mutations in the HFE2 gene encoding hemojuvelin; however, several JH families have been reported to have mutations in the HAMP gene encoding hepcidin. Here, we report a multiply consanguineous family with a father and daughter showing iron overload consistent with JH. Sequence analysis of HAMP revealed homozygosity for amino acid substitution C78T due to a c.233G > A mutation. This mutation disrupts one of eight highly conserved cysteines that are believed to be critical for the function of the active enzyme. This finding adds support to the importance of the role of these conserved cysteines in the activity of hepcidin.
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Affiliation(s)
- M B Delatycki
- Bruce Lefroy Center for Genetic Health Research, Murdoch Childrens Research Institute, University of Melbourne, Department of Paediatrics, Parkville, Victoria, Australia.
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18
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Lafrenière RG, MacDonald MLE, Dubé MP, MacFarlane J, O’Driscoll M, Brais B, Meilleur S, Brinkman RR, Dadivas O, Pape T, Platon C, Radomski C, Risler J, Thompson J, Guerra-Escobio AM, Davar G, Breakefield XO, Pimstone SN, Green R, Pryse-Phillips W, Goldberg YP, Younghusband HB, Hayden MR, Sherrington R, Rouleau GA, Samuels ME. Identification of a novel gene (HSN2) causing hereditary sensory and autonomic neuropathy type II through the Study of Canadian Genetic Isolates. Am J Hum Genet 2004; 74:1064-73. [PMID: 15060842 PMCID: PMC1181970 DOI: 10.1086/420795] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2003] [Accepted: 02/25/2004] [Indexed: 11/03/2022] Open
Abstract
Hereditary sensory and autonomic neuropathy (HSAN) type II is an autosomal recessive disorder characterized by impairment of pain, temperature, and touch sensation owing to reduction or absence of peripheral sensory neurons. We identified two large pedigrees segregating the disorder in an isolated population living in Newfoundland and performed a 5-cM genome scan. Linkage analysis identified a locus mapping to 12p13.33 with a maximum LOD score of 8.4. Haplotype sharing defined a candidate interval of 1.06 Mb containing all or part of seven annotated genes, sequencing of which failed to detect causative mutations. Comparative genomics revealed a conserved ORF corresponding to a novel gene in which we found three different truncating mutations among five families including patients from rural Quebec and Nova Scotia. This gene, termed "HSN2," consists of a single exon located within intron 8 of the PRKWNK1 gene and is transcribed from the same strand. The HSN2 protein may play a role in the development and/or maintenance of peripheral sensory neurons or their supporting Schwann cells.
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Affiliation(s)
- Ronald G. Lafrenière
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Marcia L. E. MacDonald
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Marie-Pierre Dubé
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Julie MacFarlane
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Mary O’Driscoll
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Bernard Brais
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Sébastien Meilleur
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Ryan R. Brinkman
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Owen Dadivas
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Terry Pape
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Christèle Platon
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Chris Radomski
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Jenni Risler
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Jay Thompson
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Ana-Maria Guerra-Escobio
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Gudarz Davar
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Xandra O. Breakefield
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Simon N. Pimstone
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Roger Green
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - William Pryse-Phillips
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Y. Paul Goldberg
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - H. Banfield Younghusband
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Michael R. Hayden
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Robin Sherrington
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Guy A. Rouleau
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Mark E. Samuels
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
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19
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Papanikolaou G, Samuels ME, Ludwig EH, MacDonald MLE, Franchini PL, Dubé MP, Andres L, MacFarlane J, Sakellaropoulos N, Politou M, Nemeth E, Thompson J, Risler JK, Zaborowska C, Babakaiff R, Radomski CC, Pape TD, Davidas O, Christakis J, Brissot P, Lockitch G, Ganz T, Hayden MR, Goldberg YP. Mutations in HFE2 cause iron overload in chromosome 1q-linked juvenile hemochromatosis. Nat Genet 2003; 36:77-82. [PMID: 14647275 DOI: 10.1038/ng1274] [Citation(s) in RCA: 769] [Impact Index Per Article: 36.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2003] [Accepted: 11/05/2003] [Indexed: 12/24/2022]
Abstract
Juvenile hemochromatosis is an early-onset autosomal recessive disorder of iron overload resulting in cardiomyopathy, diabetes and hypogonadism that presents in the teens and early 20s (refs. 1,2). Juvenile hemochromatosis has previously been linked to the centromeric region of chromosome 1q (refs. 3-6), a region that is incomplete in the human genome assembly. Here we report the positional cloning of the locus associated with juvenile hemochromatosis and the identification of a new gene crucial to iron metabolism. We finely mapped the recombinant interval in families of Greek descent and identified multiple deleterious mutations in a transcription unit of previously unknown function (LOC148738), now called HFE2, whose protein product we call hemojuvelin. Analysis of Greek, Canadian and French families indicated that one mutation, the amino acid substitution G320V, was observed in all three populations and accounted for two-thirds of the mutations found. HFE2 transcript expression was restricted to liver, heart and skeletal muscle, similar to that of hepcidin, a key protein implicated in iron metabolism. Urinary hepcidin levels were depressed in individuals with juvenile hemochromatosis, suggesting that hemojuvelin is probably not the hepcidin receptor. Rather, HFE2 seems to modulate hepcidin expression.
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Affiliation(s)
- George Papanikolaou
- First Department of Internal Medicine, National and Kapodistrian University of Athens, School of Medicine, Laikon General Hospital, Athens 11527, Greece
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20
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Robitaille J, MacDonald MLE, Kaykas A, Sheldahl LC, Zeisler J, Dubé MP, Zhang LH, Singaraja RR, Guernsey DL, Zheng B, Siebert LF, Hoskin-Mott A, Trese MT, Pimstone SN, Shastry BS, Moon RT, Hayden MR, Goldberg YP, Samuels ME. Mutant frizzled-4 disrupts retinal angiogenesis in familial exudative vitreoretinopathy. Nat Genet 2002; 32:326-30. [PMID: 12172548 DOI: 10.1038/ng957] [Citation(s) in RCA: 308] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2002] [Accepted: 07/16/2002] [Indexed: 11/08/2022]
Abstract
Familial exudative vitreoretinopathy (FEVR) is a hereditary ocular disorder characterized by a failure of peripheral retinal vascularization. Loci associated with FEVR map to 11q13-q23 (EVR1; OMIM 133780, ref. 1), Xp11.4 (EVR2; OMIM 305390, ref. 2) and 11p13-12 (EVR3; OMIM 605750, ref. 3). Here we have confirmed linkage to the 11q13-23 locus for autosomal dominant FEVR in one large multigenerational family and refined the disease locus to a genomic region spanning 1.55 Mb. Mutations in FZD4, encoding the putative Wnt receptor frizzled-4, segregated completely with affected individuals in the family and were detected in affected individuals from an additional unrelated family, but not in normal controls. FZD genes encode Wnt receptors, which are implicated in development and carcinogenesis. Injection of wildtype and mutated FZD4 into Xenopus laevis embryos revealed that wildtype, but not mutant, frizzled-4 activated calcium/calmodulin-dependent protein kinase II (CAMKII) and protein kinase C (PKC), components of the Wnt/Ca(2+) signaling pathway. In one of the mutants, altered subcellular trafficking led to defective signaling. These findings support a function for frizzled-4 in retinal angiogenesis and establish the first association between a Wnt receptor and human disease.
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Affiliation(s)
- Johane Robitaille
- Department of Ophthalmology, Izaak Walton Killam (IWK) Health Centre, Dalhousie University, Halifax, Nova Scotia B3H 2Y9, Canada
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21
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Bruland O, Almqvist EW, Goldberg YP, Boman H, Hayden MR, Knappskog PM. Accurate determination of the number of CAG repeats in the Huntington disease gene using a sequence-specific internal DNA standard. Clin Genet 1999; 55:198-202. [PMID: 10334474 DOI: 10.1034/j.1399-0004.1999.550308.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We have developed a sequence-specific internal DNA size standard for the accurate determination of the number of CAG repeats in the Huntington disease (HD) gene by cloning key fragments (between 15 and 64 CAG repeats) of the HD gene. These fragments, pooled to produce a sequence-specific DNA ladder, enabled us to observe the true number of CAG repeats directly, with no need for calculations. Comparison of the calculated numbers of CAG repeats in the HD gene using this sequence-specific DNA standard with a commercially available standard (GENESCAN-500 TAMRA) showed that the latter underestimated the number of CAG repeats by three when analyzed by capillary electrophoresis on the ABI 310 Genetic Analyzer (POP4 polymer). In contrast, the use of the same standard overestimated the number of CAG repeats by one when the samples were analyzed by denaturing polyacrylamide electrophoresis on ABI 377 DNA Sequencer (6% denaturing polyacrylamide gel). This suggests that our sequence-specific standard provides greater accuracy for the determination of the true number of CAG repeats in the HD gene than commercially available standards. The sequence-specific standard can be radioactively labeled and successfully replace conventional DNA size standards when analyzing polymerase chain reaction (PCR)-amplified HD alleles by denaturing polyacrylamide electrophoresis.
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Affiliation(s)
- O Bruland
- Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway
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22
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23
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Affiliation(s)
- S E Andrew
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Vancouver, B.C., Canada
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24
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Kalchman MA, Koide HB, McCutcheon K, Graham RK, Nichol K, Nishiyama K, Kazemi-Esfarjani P, Lynn FC, Wellington C, Metzler M, Goldberg YP, Kanazawa I, Gietz RD, Hayden MR. HIP1, a human homologue of S. cerevisiae Sla2p, interacts with membrane-associated huntingtin in the brain. Nat Genet 1997; 16:44-53. [PMID: 9140394 DOI: 10.1038/ng0597-44] [Citation(s) in RCA: 279] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Huntington disease (HD) is associated with the expansion of a polyglutamine tract, greater than 35 repeats, in the HD gene product, huntingtin. Here we describe a novel huntingtin interacting protein, HIP1, which co-localizes with huntingtin and shares sequence homology and biochemical characteristics with Sla2p, a protein essential for function of the cytoskeleton in Saccharomyces cerevisiae. The huntingtin-HIP1 interaction is restricted to the brain and is inversely correlated to the polyglutamine length in huntingtin. This provides the first molecular link between huntingtin and the neuronal cytoskeleton and suggests that, in HD, loss of normal huntingtin-HIP1 interaction may contribute to a defect in membrane-cytoskeletal integrity in the brain.
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Affiliation(s)
- M A Kalchman
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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25
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Goellner GM, Tester D, Thibodeau S, Almqvist E, Goldberg YP, Hayden MR, McMurray CT. Different mechanisms underlie DNA instability in Huntington disease and colorectal cancer. Am J Hum Genet 1997; 60:879-90. [PMID: 9106534 PMCID: PMC1712468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Two recent lines of evidence raise the possibility that instability in germ-line or somatic cells arises by a common mechanism that involves defective mismatch repair. Mutations in mismatch-repair proteins are known to cause instability in hereditary nonpolyposis colorectal cancer, instability that is physically similar to germ-line instability observed in Huntington disease (HD). Furthermore, both germ-line and somatic-cell instability are likely to be mitotic defects, the former occurring early in embryogenesis. To test the hypothesis that defective repair is a common prerequisite for instability, we have utilized two disease groups that represent different instability "conditions." Germ-line instability within simple tandem repeats (STR) at 10 loci in 29 HD families were compared with somatic instability at the same loci in 26 colon cancer (CC) patients with identified or suspected defects in mismatch-repair enzymes. HD is known to be caused by expansion within the CAG repeat of the locus, but the extent or pattern of STR instability outside this region has not been examined systematically. We find a distinctly different pattern of STR mutation in the two disease groups, suggesting different mechanisms. Instability in HD is generally confined to a single locus, whereas instability is widespread for the same loci in CC. Our data do not support a causative role for defective mismatch-repair enzymes in instability associated with HD; rather, our data are consistent with a model in which DNA structure may inhibit normal mismatch repair at the expansion site.
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Affiliation(s)
- G M Goellner
- Molecular Neuroscience Program, Mayo Foundation, Rochester, MN 55905, USA
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26
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Chong SS, Almqvist E, Telenius H, LaTray L, Nichol K, Bourdelat-Parks B, Goldberg YP, Haddad BR, Richards F, Sillence D, Greenberg CR, Ives E, Van den Engh G, Hughes MR, Hayden MR. Contribution of DNA sequence and CAG size to mutation frequencies of intermediate alleles for Huntington disease: evidence from single sperm analyses. Hum Mol Genet 1997; 6:301-9. [PMID: 9063751 DOI: 10.1093/hmg/6.2.301] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
New mutations for Huntington disease (HD) arise from intermediate alleles (IAs) with between 29 and 35 CAG repeats that expand on transmission through the paternal germline to 36 CAGs or greater. Using single sperm analysis, we have assessed CAG mutation frequencies for four IAs in families with sporadic HD (IANM) and IAs ascertained from the general population (IAGP) by analyzing 1161 single sperm from three persons. We show that IANM are more unstable than IAGP with identical size and sequence. Furthermore, comparison of different sized IAs and IAs with different sequences between the CAG and the adjacent CCG tracts indicates that DNA sequence is a major influence on CAG stability. These studies provide estimates of the likelihood of expansion of IANM and IAGP to > or = 36 CAG repeats for these individuals. For an IA with a CAG of 35 in this family with sporadic HD, the likelihood for siblings to inherit a recurrent mutation > or = 36 CAG is approximately 10%. For IAGP of a similar size, the risk of inheriting an expanded allele of > or = 36 CAG through the paternal germline is approximately 6%. These risk estimates are higher than previously reported and provide additional information for counselling in these families. Further studies on persons with IAs will be needed to determine whether these results can be generalized to other families.
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Affiliation(s)
- S S Chong
- National Center for Human Genome Research, National Institutes of Health, Bethesda, MD 29892-4470, USA
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27
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Steyn K, Goldberg YP, Kotze MJ, Steyn M, Swanepoel AS, Fourie JM, Coetzee GA, Van der Westhuyzen DR. Estimation of the prevalence of familial hypercholesterolaemia in a rural Afrikaner community by direct screening for three Afrikaner founder low density lipoprotein receptor gene mutations. Hum Genet 1996; 98:479-84. [PMID: 8792826 DOI: 10.1007/s004390050243] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We have determined the prevalence of familial hypercholesterolaemia (FH) in a rural Afrikaner community by means of direct DNA screening for three founder-related Afrikaner low density lipoprotein (LDL) receptor gene mutations. A random sample of 1612 persons, aged 15-64 years, was selected as a subsample of 4583 subjects from an Afrikaner community living in the south-western Cape, South Africa. Participants who had a total serum cholesterol (TC) in the high TC category as defined in the consensus recommendations by the Southern African Heart Foundation, were screened for three founder-related LDL receptor gene mutations, causing FH in 90% of Afrikaners. Of the subsample, 201 participants (12.5%) had TC levels above the 80th percentile. In this group the combined prevalence of the three common Afrikaner LDL receptor gene defects (D206E, FH Afrikaner-1; V408M, FH Afrikaner-2; D154N, FH Afrikaner-3) was calculated as 1: 83. When taking into account the reported background prevalence of other FH gene defects of 1:500 in this community, their overall prevalence of FH was estimated to be 1:72. The significant differences found between the FH patients and other high risk patients with raised cholesterol levels were higher TC and LDL cholesterol levels and lower high density lipoprotein cholesterol levels in FH patients. The treatment status of the molecularly identified FH patients and other hypercholesterolaemic persons suggests that this condition is inadequately diagnosed and poorly managed in this study population. An extrapolation to the entire South African population suggests that there are about 112000 FH patients in the country who are under-diagnosed as a group and therefore not receiving the care that would help to reduce the burden of FH-associated ischaemic heart disease in South Africa.
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Affiliation(s)
- K Steyn
- Medical Research Council, Tygerberg, South Africa
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28
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Abstract
The mutation underlying Huntington disease (HD) is CAG expansion beyond 35 repeats within a novel gene. Recently, new insights into the role of the HD protein (huntingtin) in the pathogenesis of HD have emerged. The CAG is translated and expression of mutant huntingtin is essential for neuronal death. Huntingtin is crucial for normal development and may be regarded as a cell survival gene. Huntingtin is specifically cleaved during apoptosis by a key cysteine protease, apopain, known to play a pivotal role in apoptotic cell death. The rate of cleavage is enhanced by longer polyglutamine tracts, suggesting that inappropriate apoptosis underlies HD. Recently, three proteins have been identified and have been shown specifically to interact with huntingtin, two of these interactions being influenced by CAG length. Several different approaches to develop an animal model for HD include cDNA and YAC transgenics, as well as 'knock-in' strategies. Such a model will be critical for the understanding of the natural history of HD and for the testing of new therapeutic modalities.
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Affiliation(s)
- J Nasir
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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29
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Kalchman MA, Graham RK, Xia G, Koide HB, Hodgson JG, Graham KC, Goldberg YP, Gietz RD, Pickart CM, Hayden MR. Huntingtin is ubiquitinated and interacts with a specific ubiquitin-conjugating enzyme. J Biol Chem 1996; 271:19385-94. [PMID: 8702625 DOI: 10.1074/jbc.271.32.19385] [Citation(s) in RCA: 254] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Using the yeast two-hybrid system, we have identified a human ubiquitin-conjugating enzyme (hE2-25K) as a protein that interacts with the gene product for Huntington disease (HD) (Huntingtin). This protein has complete amino acid identity with the bovine E2-25K protein and has striking similarity to the UBC-1, -4 and -5 enzymes of Saccharomyces cerevisiae. This protein is highly expressed in brain and a slightly larger protein recognized by an anti-E2-25K polyclonal antibody is selectively expressed in brain regions affected in HD. The huntingtin-E2-25K interaction is not obviously modulated by CAG length. We also demonstrate that huntingtin is ubiquitinated. These findings have implications for the regulated catabolism of the gene product for HD.
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Affiliation(s)
- M A Kalchman
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
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30
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Goldberg YP, Nicholson DW, Rasper DM, Kalchman MA, Koide HB, Graham RK, Bromm M, Kazemi-Esfarjani P, Thornberry NA, Vaillancourt JP, Hayden MR. Cleavage of huntingtin by apopain, a proapoptotic cysteine protease, is modulated by the polyglutamine tract. Nat Genet 1996; 13:442-9. [PMID: 8696339 DOI: 10.1038/ng0896-442] [Citation(s) in RCA: 409] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Apoptosis has recently been recognized as a mode of cell death in Huntington disease (HD). Apopain, a human counterpart of the nematode cysteine protease death-gene product, CED-3, has a key role in proteolytic events leading to apoptosis. Here we show that apoptotic extracts and apopain itself specifically cleave the HD gene product, huntingtin. The rate of cleavage increases with the length of the huntingtin polyglutamine tract, providing an explanation for the gain-of-function associated with CAG expansion. Our results show that huntingtin is cleaved by cysteine proteases and suggest that HD might be a disorder of inappropriate apoptosis.
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Affiliation(s)
- Y P Goldberg
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
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31
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Goldberg YP, Kalchman MA, Metzler M, Nasir J, Zeisler J, Graham R, Koide HB, O'Kusky J, Sharp AH, Ross CA, Jirik F, Hayden MR. Absence of disease phenotype and intergenerational stability of the CAG repeat in transgenic mice expressing the human Huntington disease transcript. Hum Mol Genet 1996; 5:177-85. [PMID: 8824873 DOI: 10.1093/hmg/5.2.177] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The mutation underlying Huntington disease (HD) is CAG expansion in the first exon of the HD gene. In order to investigate the role of CAG expansion in the pathogenesis of HD, we have produced transgenic mice containing the full length human HD cDNA with 44 CAG repeats. By 1 year, these mice have no behavioral abnormalities and morphometric analysis at 6 (one animal) and 9 (two animals) months age revealed no changes. Despite high levels of mRNA expression, there was no evidence of the HD gene product in any of these transgenic mice. In vitro transfection studies indicated that the inclusion of 120 bp of the 5' UTR in the cDNA construct and the presence of a frameshift mutation at nucleotide 2349 prevented expression of the HD cDNA. These findings suggest that the pathogenesis of HD is not mediated through DNA-protein interaction and that presence of the RNA transcript with an expanded CAG repeat is insufficient to cause the disease. Rather, translation of the CAG is crucial for the pathogenesis of HD. In contrast to that seen in humans, the CAG repeat in these mice was remarkably stable in 97 meioses. This suggests that genomic sequences may play a critical role in influencing repeat instability.
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Affiliation(s)
- Y P Goldberg
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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32
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Goldberg YP, McMurray CT, Zeisler J, Almqvist E, Sillence D, Richards F, Gacy AM, Buchanan J, Telenius H, Hayden MR. Increased instability of intermediate alleles in families with sporadic Huntington disease compared to similar sized intermediate alleles in the general population. Hum Mol Genet 1995; 4:1911-8. [PMID: 8595415 DOI: 10.1093/hmg/4.10.1911] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We have directly compared intergenerational stability of intermediate alleles (IAs) derived from new mutation families (IANM) for Huntington disease (HD) with IAs in the general population (IAGP) which occur in approximately 1 in 50 persons. Analysis of meiotic events in blood and sperm reveals that IANM are significantly more unstable than IAGP despite similar size. However, for both IANM and IAGP CAG changes were small and risks for inheriting an expansion into the HD affected range were low. Sequence analysis reveals that the CAG tract is generally interrupted by a penultimate CAA in IAGP, IANM and alleles in the affected range. In one new mutation family, however, two A-->G mutations result in a pure CAG tract which is associated with very marked instability. These mutations alter the predicted DNA hairpin structure with a predicted increase in the likelihood of large expansion, supporting the model that hairpin loop formation plays an important role in trinucleotide instability.
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Affiliation(s)
- Y P Goldberg
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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33
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Kremer B, Almqvist E, Theilmann J, Spence N, Telenius H, Goldberg YP, Hayden MR. Sex-dependent mechanisms for expansions and contractions of the CAG repeat on affected Huntington disease chromosomes. Am J Hum Genet 1995; 57:343-50. [PMID: 7668260 PMCID: PMC1801544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A total of 254 affected parent-child pairs with Huntington disease (HD) and 440 parent-child pairs with CAG size in the normal range were assessed to determine the nature and frequency of intergenerational CAG changes in the HD gene. Intergenerational CAG changes are extremely rare (3/440 [0.68%]) on normal chromosomes. In contrast, on HD chromosomes, changes in CAG size occur in approximately 70% of meioses on HD chromosomes, with expansions accounting for 73% of these changes. These intergenerational CAG changes make a significant but minor contribution to changes in age at onset (r2 = .19). The size of the CAG repeat influenced larger intergenerational expansions (> 7 CAG repeats), but the likelihood of smaller expansions or contractions was not influenced by CAG size. Large expansions (> 7 CAG repeats) occur almost exclusively through paternal transmission (0.96%; P < 10(-7)), while offspring of affected mothers are more likely to show no change (P = .01) or contractions in CAG size (P = .002). This study demonstrates that sex of the transmitting parent is the major determinant for CAG intergenerational changes in the HD gene. Similar paternal sex effects are seen in the evolution of new mutations for HD from intermediate alleles and for large expansions on affected chromosomes. Affected mothers almost never transmit a significantly expanded CAG repeat, despite the fact that many have similar large-sized alleles, compared with affected fathers. The sex-dependent effects of major expansion and contractions of the CAG repeat in the HD gene implicate different effects of gametogenesis, in males versus females, on intergenerational CAG repeat stability.
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Affiliation(s)
- B Kremer
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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34
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Lin B, Nasir J, Kalchman MA, McDonald H, Zeisler J, Goldberg YP, Hayden MR. Structural analysis of the 5' region of mouse and human Huntington disease genes reveals conservation of putative promoter region and di- and trinucleotide polymorphisms. Genomics 1995; 25:707-15. [PMID: 7759106 DOI: 10.1016/0888-7543(95)80014-d] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We have previously cloned and characterized the murine homologue of the Huntington disease (HD) gene and shown that it maps to mouse chromosome 5 within a region of conserved synteny with human chromosome 4p16.3. Here we present a detailed comparison of the sequence of the putative promoter and the organization of the 5' genomic region of the murine (Hdh) and human HD genes encompassing the first five exons. We show that in this region these two genes share identical exon boundaries, but have different-size introns. Two dinucleotide (CT) and one trinucleotide intronic polymorphism in Hdh and an intronic CA polymorphism in the HD gene were identified. Comparison of 940-bp sequence 5' to the putative translation start site reveals a highly conserved region (78.8% nucleotide identity) between Hdh and the HD gene from nucleotide -56 to -206 (of Hdh). Neither Hdh nor the HD gene have typical TATA or CCAAT elements, but both show one putative AP2 binding site and numerous potential Sp1 binding sites. The high sequence identity between Hdh and the HD gene for approximately 200 bp 5' to the putative translation start site indicates that these sequences may play a role in regulating expression of the Huntington disease gene.
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Affiliation(s)
- B Lin
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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35
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Almqvist E, Spence N, Nichol K, Andrew SE, Vesa J, Peltonen L, Anvret M, Goto J, Kanazawa I, Goldberg YP. Ancestral differences in the distribution of the delta 2642 glutamic acid polymorphism is associated with varying CAG repeat lengths on normal chromosomes: insights into the genetic evolution of Huntington disease. Hum Mol Genet 1995; 4:207-14. [PMID: 7757069 DOI: 10.1093/hmg/4.2.207] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
This study addresses genetic factors associated with normal variation of the CAG repeat in the Huntington disease (HD) gene. To achieve this, we have studied patterns of variation of three trinucleotide repeats in the HD gene including the CAG and adjacent CCG repeats as well as a GAG polymorphism at residue 2642 (delta 2642). We have previously demonstrated that variation in the CCG repeat is associated with variation of the CAG repeat length on normal chromosomes. Here we show that differences in the GAG trinucleotide polymorphism at residue 2642 is also significantly correlated with CAG size on normal chromosomes. The B allele which is associated with higher CAG repeat lengths on normal chromosomes is markedly enriched on affected chromosomes. Furthermore, this glutamic acid polymorphism shows significant variation in different ancestries and is absent in chromosomes of Japanese, Black and Chinese descent. Haplotype analysis of both the CCG and delta 2642 polymorphisms have indicated that both are independently associated with differences in CAG length on normal chromosomes. These findings lead to a model for the genetic evolution of new mutations for HD preferentially occurring on normal chromosomes with higher CAG repeat lengths and a CCG repeat length of seven and/or a deletion of the glutamic acid residue at delta 2642. This study also provides additional evidence for genetic contributions to demographic differences in prevalence rates for HD.
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Affiliation(s)
- E Almqvist
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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36
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Lin B, Nasir J, McDonald H, Graham R, Rommens JM, Goldberg YP, Hayden MR. Genomic organization of the human alpha-adducin gene and its alternately spliced isoforms. Genomics 1995; 25:93-9. [PMID: 7774961 DOI: 10.1016/0888-7543(95)80113-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The cDNA for the human alpha-adducin gene has been cloned, and different alternately spliced forms have been identified. We report the complete genomic organization of the human alpha-adducin gene and these alternately spliced forms. The human alpha-adducin gene, spanning approximately 85 kb, consists of 16 exons ranging in size from 34 to 1892 bp. One of the spliced forms of the human alpha-adducin gene results from alternate use of the 5' splice donor site for exon 10, while another results in a truncated protein following insertion of 34 bp comprising exon 15, followed by a premature stop codon. This alternate spliced form of alpha-adducin is predicted to result in an altered carboxyl terminus that would eliminate a protein kinase and calmodulin binding site. Seven nucleotide substitutions and 4 insertion/deletions were also identified. The 5' region of the human alpha-adducin gene contains one Sp1 site, two AP2 sites, and two CAAT boxes. No TATA box was apparent, consistent with features of a housekeeping gene. We have mapped another cDNA within the first intron of the human alpha-adducin gene, suggesting overlapping genes in this 4p16.3 genomic region.
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Affiliation(s)
- B Lin
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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37
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Squitieri F, Andrew SE, Goldberg YP, Kremer B, Spence N, Zeisler J, Nichol K, Theilmann J, Greenberg J, Goto J. DNA haplotype analysis of Huntington disease reveals clues to the origins and mechanisms of CAG expansion and reasons for geographic variations of prevalence. Hum Mol Genet 1994; 3:2103-14. [PMID: 7881406 DOI: 10.1093/hmg/3.12.2103] [Citation(s) in RCA: 115] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
This study of allelic association using three intra- and two extragenic markers within 150 kb of the Huntington disease (HD) mutation has provided evidence for linkage disequilibrium for four of five markers. Haplotype analysis of 67 HD families using markers in strong linkage disequilibrium with HD identified two haplotypes underlying 77.6% of HD chromosomes. Normal chromosomes with these two haplotypes had a mean number of CAG repeats significantly larger than and an altered distribution of CAG repeats compared with other normal chromosomes. Furthermore, haplotype analysis of five new mutation families reveals that HD has arisen on these same two chromosomal haplotypes. These findings suggest that HD arises more frequently on chromosomes with specific DNA haplotypes and higher CAG repeat lengths. We then studied CAG and CCG repeat lengths in the HD gene on 896 control chromosomes from different ancestries to determine whether the markedly reduced frequency of HD in Finland, Japan, China and African Blacks is associated with an altered frequency of DNA haplotypes and subsequently lower CAG lengths on control chromosomes compared to populations of Western European descent. The results show a highly significant inverse relationship between CAG and CCG repeat lengths. In populations with lowered prevalence rates of HD, CAG repeat lengths are smaller and the distribution of CCG alleles is markedly different from Western European populations. These findings suggest that, in addition to European emigration, new mutations make a contribution to geographical variation of prevalence rates and is consistent with a multistep model of HD developing from normal chromosomes with higher CAG repeat lengths.
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Affiliation(s)
- F Squitieri
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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38
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Abstract
The past year has witnessed outstanding developments in research on Huntington's disease (HD). A gene was identified that contains an expanded CAG trinucleotide repeat on HD chromosomes. Patterns of expression of this gene and the nature of two transcripts were identified. CAG repeat size ranges between 36 and 121 in affected persons, and it is highly sensitive and specific marker for HD. A correlation between CAG repeat size and the age of onset of HD was demonstrated. Identification of this mutation has facilitated direct approaches to predictive testing for HD. The new mutation rate, previously deemed to be exceedingly rare, is now shown to be responsible for up to 3% of affected persons. Although the mechanism by which CAG repeat length induces neuronal death is not known, there is evidence that the pathogenesis involves a gain of function in the HD gene.
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Affiliation(s)
- Y P Goldberg
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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39
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Andrew SE, Goldberg YP, Kremer B, Squitieri F, Theilmann J, Zeisler J, Telenius H, Adam S, Almquist E, Anvret M. Huntington disease without CAG expansion: phenocopies or errors in assignment? Am J Hum Genet 1994; 54:852-63. [PMID: 8178825 PMCID: PMC1918249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Huntington disease (HD) has been shown to be associated with an expanded CAG repeat within a novel gene on 4p16.3 (IT15). A total of 30 of 1,022 affected persons (2.9% of our cohort) did not have an expanded CAG in the disease range. The reasons for not observing expansion in affected individuals are important for determining the sensitivity of using repeat length both for diagnosis of affected patients and for predictive testing programs and may have biological relevance for the understanding of the molecular mechanism underlying HD. Here we show that the majority (18) of the individuals with normal sized alleles represent misdiagnosis, sample mix-up, or clerical error. The remaining 12 patients represent possible phenocopies for HD. In at least four cases, family studies of these phenocopies excluded 4p16.3 as the region responsible for the phenotype. Mutations in the HD gene that are other than CAG expansion have not been excluded for the remaining eight cases; however, in as many as seven of these persons, retrospective review of these patients' clinical features identified characteristics not typical for HD. This study shows that on rare occasions mutations in other, as-yet-undefined genes can present with a clinical phenotype very similar to that of HD.
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Affiliation(s)
- S E Andrew
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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40
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Telenius H, Kremer B, Goldberg YP, Theilmann J, Andrew SE, Zeisler J, Adam S, Greenberg C, Ives EJ, Clarke LA. Somatic and gonadal mosaicism of the Huntington disease gene CAG repeat in brain and sperm. Nat Genet 1994; 6:409-14. [PMID: 8054984 DOI: 10.1038/ng0494-409] [Citation(s) in RCA: 274] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Huntington disease is associated with an unstable and expanded (CAG) trinucleotide repeat. We have analysed the CAG expansion in different tissues from 12 affected individuals. All tissues examined were found to display some repeat mosaicism, with the greatest levels detected in brain and sperm. Regions within the brain showing most obvious neuropathology, such as the basal ganglia and the cerebral cortex, displayed the greatest mosaicism, whereas the cerebellar cortex, which is seldom involved, displayed the lowest degree of CAG instability. In two cases of childhood onset disease we detected differences of 8 and 13 trinucleotides between the cerebellum and other regions of the brain. Our results provide evidence for tissue specific instability of the CAG repeat, with the largest CAG repeat lengths in affected regions of the brain.
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Affiliation(s)
- H Telenius
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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41
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Andrew SE, Goldberg YP, Theilmann J, Zeisler J, Hayden MR. A CCG repeat polymorphism adjacent to the CAG repeat in the Huntington disease gene: implications for diagnostic accuracy and predictive testing. Hum Mol Genet 1994; 3:65-7. [PMID: 8162053 DOI: 10.1093/hmg/3.1.65] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The polymorphic CAG repeat that is expanded on Huntington disease (HD) chromosomes is flanked by a CCG repeat. Here we show that this CCG tract, previously assumed to be invariant at seven CCG repeats, is also polymorphic. We have identified five CCG alleles from 205 normal chromosomes, with 137 (67%) having alleles of seven repeats, five (2%) with nine repeats, 61 (30%) with 10 repeats, one (0.5%) with 11 repeats and one (0.5%) with 12 repeats. In contrast, analysis of 113 HD chromosomes revealed that the majority (105 chromosomes, 93%) contained seven CCG repeats, while the remaining eight chromosomes (7%) had allele sizes of 10 CCG repeats. Despite evidence that both CAG and CCG are polymorphic on normal chromosomes, we have found that it is only the CAG length that has a significant impact on age of onset. The discovery of larger sized CCG alleles, however, has significant implications for the assessment of CAG repeat length, particularly for persons with estimated CAG size of 36-42 repeats, since an overestimation of CAG length in this range could result in erroneous information being imparted to patients.
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Affiliation(s)
- S E Andrew
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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42
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Abstract
Late onset Huntington's disease is characterised by onset of symptoms after the age of 50 and is usually associated with a milder course. We have analysed the CAG trinucleotide repeat within the HD gene in 133 late onset patients from 107 extended families. The median upper allele size for the CAG repeat was 42 with a range of 38 to 48 repeats. A significant negative correlation (r = -0.29, p = 0.001) was found between the length of repeat and age of onset for the total cohort. However, for persons with age of onset greater than 60, no significant correlation was found. In addition, no significant correlation was found between age of onset and size of the lower allele and the sex of the affected parent or grandparent. There was no preponderance of maternal descent for late onset cases in this series. This study shows that variation in repeat length only accounts for approximately 7% of the variation in age of onset for persons beyond the age of 50 and clearly shows how with increasing onset age the effect of the repeat length on this onset age seems to diminish.
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Affiliation(s)
- B Kremer
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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43
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Goldberg YP, Andrew SE, Theilmann J, Kremer B, Squitieri F, Telenius H, Brown JD, Hayden MR. Familial predisposition to recurrent mutations causing Huntington's disease: genetic risk to sibs of sporadic cases. J Med Genet 1993; 30:987-90. [PMID: 8133509 PMCID: PMC1016629 DOI: 10.1136/jmg.30.12.987] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Huntington's disease (HD) is associated with expansion of a CAG repeat in a new gene. We have recently defined a premutation in a paternal allele of 30 to 38 CAG repeats in the HD gene which is greater than that seen in the general population (< 30 repeats) but below the range seen in patients with HD (> 38). These intermediate alleles are unstable during transmission through the germline and in sporadic cases expand to the full mutation associated with the clinical phenotype of HD. Here we have analysed three new mutation families where, in each, the proband and at least one sib have CAG sizes in the HD range. In one of these families, two sibs with expanded CAG repeats are both clinically affected with HD, thus presenting a pseudorecessive pattern of inheritance. In all three families the parental intermediate allele has expanded in more than one offspring, thus showing a previously unrecognised risk of inheriting HD to sibs of sporadic cases of HD.
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Affiliation(s)
- Y P Goldberg
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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44
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Goldberg YP, Kremer B, Andrew SE, Theilmann J, Graham RK, Squitieri F, Telenius H, Adam S, Sajoo A, Starr E. Molecular analysis of new mutations for Huntington's disease: intermediate alleles and sex of origin effects. Nat Genet 1993; 5:174-9. [PMID: 8252043 DOI: 10.1038/ng1093-174] [Citation(s) in RCA: 182] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Huntington's disease (HD) is associated with expansion of a CAG repeat in a novel gene. We have assessed 21 sporadic cases of HD to investigate sequential events underlying HD. We show the existence of an intermediate allele (IA) in parental alleles of 30-38 CAG repeats in the HD gene which is greater than usually seen in the general population but below the range seen in patients with HD. These IAs are meiotically unstable and in the sporadic cases, expand to the full mutation associated with the phenotype of HD. This expansion has been shown to occur only during transmission through the male germline and is associated with advanced paternal age. These findings suggest that new mutations for HD are more frequent than prior estimates and indicate a previously unrecognized risk of inheriting HD to siblings of sporadic cases of HD and their children.
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Affiliation(s)
- Y P Goldberg
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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45
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Lin B, Rommens JM, Graham RK, Kalchman M, MacDonald H, Nasir J, Delaney A, Goldberg YP, Hayden MR. Differential 3' polyadenylation of the Huntington disease gene results in two mRNA species with variable tissue expression. Hum Mol Genet 1993; 2:1541-5. [PMID: 7903579 DOI: 10.1093/hmg/2.10.1541] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Recently a novel gene containing a CAG trinucleotide repeat that is expanded on HD chromosomes has been identified(1). This gene was shown to detect a single transcript of 10-11 kb by RNA hybridization. We have however, previously identified three cDNAs which are part of the same gene that have been shown to detect two distinct transcripts of 10 kb and one that is significantly larger(2,3). These different mRNA species could be due to use of alternate transcription start sites, alternate splicing or selection of different polyadenylation sites. We have identified cDNA clones spanning the HD gene including two (HD12 and HD14) that share identical protein coding sequences but differ in size and sequence of their 3' untranslated region. HD14 has 3,360 base pairs of additional sequence distal to the previously published 3' end (1). RNA hybridization has revealed that the larger 13.7 kb fragment is the predominant transcript in human brain. cDNA fragments unique to HD14 detected only the larger transcript. Sequence analysis identified two different putative polyadenylation sequences at position 10,326 and 13,645 of the HD14 cDNA. These findings indicate that the two observed mRNA species originate from a single gene and that differential polyadenylation leads to transcripts of different size. The relative increased abundance of the larger transcript in human brain may provide some insights into the mechanism by which a widely expressed gene may exert tissue specific effects.
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Affiliation(s)
- B Lin
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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46
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Andrew SE, Goldberg YP, Kremer B, Telenius H, Theilmann J, Adam S, Starr E, Squitieri F, Lin B, Kalchman MA. The relationship between trinucleotide (CAG) repeat length and clinical features of Huntington's disease. Nat Genet 1993; 4:398-403. [PMID: 8401589 DOI: 10.1038/ng0893-398] [Citation(s) in RCA: 697] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Huntington's disease (HD) is associated with the expansion of a CAG trinucleotide repeat in a novel gene. We have assessed 360 HD individuals from 259 unrelated families and found a highly significant correlation (r = 0.70, p = 10(-7)) between the age of onset and the repeat length, which accounts for approximately 50% of the variation in the age of onset. Significant associations were also found between repeat length and age of death and onset of other clinical features. Sib pair and parent-child analysis revealed that the CAG repeat demonstrates only mild instability. Affected HD siblings had significant correlations for trinucleotide expansion (r = 0.66, p < 0.001) which was not apparent for affected parent-child pairs.
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Affiliation(s)
- S E Andrew
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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47
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Hutchinson GB, Andrew SE, McDonald H, Goldberg YP, Graham R, Rommens JM, Hayden MR. An Alu element retroposition in two families with Huntington disease defines a new active Alu subfamily. Nucleic Acids Res 1993; 21:3379-83. [PMID: 8393987 PMCID: PMC331434 DOI: 10.1093/nar/21.15.3379] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Alu repetitive elements represent the most common short interspersed elements (SINEs) found in primates, with an estimated 500,000 members in the haploid human genome. Considerable evidence has accumulated that these elements have dispersed in the genome by active transcription followed by retroposition, and that this process is ongoing. Sequence variation between the individual elements has lead to the hierarchical classification of Alu repeats into families and subfamilies. Young subfamilies that are still being actively transposed are of considerable interest, and the identification of one such subfamily (designated 'PV') has lead to the hypothesis that the most recent retroposition events are due to a single master Alu source gene. In the course of our search for the gene causing Huntington disease, we have detected an Alu retroposition event in two families. Sequence analysis demonstrates that this Alu element is not a member of the PV subfamily, but is similar to 5 other Alu elements in the GenBank database. Together, these Alu elements, all of which contain a 7 base-pair internal duplication, define a distinct subfamily, designated as the Sb2 subfamily, providing evidence for a second actively retroposing Alu source gene. These data provide support for multiple source genes for Alu retroposition in the human genome.
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Affiliation(s)
- G B Hutchinson
- Department of Medical Genetics, University of British Columbia, Vancouver
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48
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Rommens JM, Lin B, Hutchinson GB, Andrew SE, Goldberg YP, Glaves ML, Graham R, Lai V, McArthur J, Nasir J. A transcription map of the region containing the Huntington disease gene. Hum Mol Genet 1993; 2:901-7. [PMID: 7689900 DOI: 10.1093/hmg/2.7.901] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A transcription map of the Huntington disease gene region was generated by a direct cDNA selection strategy using genomic DNA from the 4p16.3 region surrounding the D4S95 and D4S127 loci. A total of 58 cDNA fragments were obtained from cDNAs derived from fetal brain, frontal cortex, liver and bone marrow following hybridization to overlapping YACs from this region. These cDNA clones were aligned into transcription units by hybridization to specific mRNAs, by sequence overlap and by physical mapping onto overlapping YAC clones. Nine separate transcription units spanning approximately one megabase were detected by RNA hybridization. They represent a minimum number of genes in this region and do not include those genes expressed specifically in tissues not used for the hybridization. The transcription map that is provided by the cDNA segments will lead to the generation of a detailed gene map of this region.
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Affiliation(s)
- J M Rommens
- Department of Genetics, Hospital for Sick Children, Toronto, Ontario, Canada
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49
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Goldberg YP, Andrew SE, Clarke LA, Hayden MR. A PCR method for accurate assessment of trinucleotide repeat expansion in Huntington disease. Hum Mol Genet 1993; 2:635-6. [PMID: 8353482 DOI: 10.1093/hmg/2.6.635] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Affiliation(s)
- Y P Goldberg
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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50
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Goldberg YP, Rommens JM, Andrew SE, Hutchinson GB, Lin B, Theilmann J, Graham R, Glaves ML, Starr E, McDonald H. Identification of an Alu retrotransposition event in close proximity to a strong candidate gene for Huntington's disease. Nature 1993; 362:370-3. [PMID: 8384324 DOI: 10.1038/362370a0] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Huntington's disease (HD) is a late-onset autosomal dominant neuropsychiatric disorder presenting in mid-adult life with personality disturbance and involuntary movements, cognitive and affective disturbance, and inexorable progression to death. The underlying genetic defect has been mapped to chromosomal band 4p16.3 (refs 2, 3). Analysis of specific recombination events in some families with HD has further refined the location of the HD defect to a 2.2 megabase DNA interval. Using a direct complementary DNA selection strategy we have identified at least seven transcriptional units within the minimal region believed to contain the HD gene. Screening with one of the cDNA clones identified an Alu insertion in genomic DNA from two persons with HD which showed complete cosegregation with the disease in these families but was not found in 1,000 control chromosomes. Two genes including the previously identified alpha-adducin gene and another that encodes for a 12-kilobase transcript, map in close proximity to the Alu insertion site. The 12-kilobase transcript should be regarded as a strong candidate for the HD gene.
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Affiliation(s)
- Y P Goldberg
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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