1
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Leung M, Sanchez-Castillo M, Belnap N, Naymik M, Bonfitto A, Sloan J, Hassett K, Jepsen WM, Sankaramoorthy A, Stewart TM, Foley JR, Rangasamy S, Huentelman MJ, Narayanan V, Ramsey K. Snyder-Robinson syndrome presenting with learning disability, epilepsy, and osteoporosis: a novel SMS gene variant. RARE : OPEN RESEARCH IN RARE DISEASES 2023; 2:100017. [PMID: 38770537 PMCID: PMC11105150 DOI: 10.1016/j.rare.2023.100017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Snyder-Robinson syndrome (SRS) is a rare X-linked recessive disorder characterized by a collection of clinical features including mild to severe intellectual disability, hypertonia, marfanoid habitus, facial asymmetry, osteoporosis, developmental delay and seizures. Whole genome sequencing (WGS) identified a mutation in the spermine synthase (SMS) gene (c.746 A>G, p.Tyr249Cys) in a male with kyphosis, seizures, and osteoporosis. His phenotype is unique in that he does not have intellectual disability (ID) but does have a mild learning disability. This case demonstrates a milder presentation of SRS and expands the phenotype beyond the reported literature.
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Affiliation(s)
- Megumi Leung
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, United States
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, United States
| | - Meredith Sanchez-Castillo
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, United States
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, United States
| | - Newell Belnap
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, United States
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, United States
| | - Marcus Naymik
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, United States
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, United States
| | - Anna Bonfitto
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, United States
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, United States
| | - Jennifer Sloan
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, United States
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, United States
| | - Katie Hassett
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, United States
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, United States
| | - Wayne M Jepsen
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, United States
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, United States
| | - Aravind Sankaramoorthy
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, United States
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, United States
| | - Tracy Murray Stewart
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Jackson R Foley
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Sampathkumar Rangasamy
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, United States
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, United States
| | - Matthew J Huentelman
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, United States
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, United States
| | - Vinodh Narayanan
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, United States
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, United States
| | - Keri Ramsey
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, United States
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, United States
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2
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Stewart TM, Foley JR, Holbert CE, Khomutov M, Rastkari N, Tao X, Khomutov AR, Zhai RG, Casero RA. Difluoromethylornithine rebalances aberrant polyamine ratios in Snyder-Robinson syndrome. EMBO Mol Med 2023; 15:e17833. [PMID: 37702369 PMCID: PMC10630878 DOI: 10.15252/emmm.202317833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 08/18/2023] [Accepted: 08/30/2023] [Indexed: 09/14/2023] Open
Abstract
Snyder-Robinson syndrome (SRS) results from mutations in spermine synthase (SMS), which converts the polyamine spermidine into spermine. Affecting primarily males, common manifestations of SRS include intellectual disability, osteoporosis, hypotonia, and seizures. Symptom management is the only treatment. Reduced SMS activity causes spermidine accumulation while spermine levels are reduced. The resulting exaggerated spermidine:spermine ratio is a biochemical hallmark of SRS that tends to correlate with symptom severity. Our studies aim to pharmacologically manipulate polyamine metabolism to correct this imbalance as a therapeutic strategy for SRS. Here we report the repurposing of 2-difluoromethylornithine (DFMO), an FDA-approved inhibitor of polyamine biosynthesis, in rebalancing spermidine:spermine ratios in SRS patient cells. Mechanistic in vitro studies demonstrate that, while reducing spermidine biosynthesis, DFMO also stimulates the conversion of spermidine into spermine in hypomorphic SMS cells and induces uptake of exogenous spermine, altogether reducing the aberrant ratios. In a Drosophila SRS model characterized by reduced lifespan, DFMO improves longevity. As nearly all SRS patient mutations are hypomorphic, these studies form a strong foundation for translational studies with significant therapeutic potential.
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Affiliation(s)
- Tracy Murray Stewart
- Sidney Kimmel Comprehensive Cancer CenterJohns Hopkins School of MedicineBaltimoreMDUSA
| | - Jackson R Foley
- Sidney Kimmel Comprehensive Cancer CenterJohns Hopkins School of MedicineBaltimoreMDUSA
| | - Cassandra E Holbert
- Sidney Kimmel Comprehensive Cancer CenterJohns Hopkins School of MedicineBaltimoreMDUSA
| | - Maxim Khomutov
- Engelhardt Institute of Molecular BiologyRussian Academy of SciencesMoscowRussia
| | - Noushin Rastkari
- Sidney Kimmel Comprehensive Cancer CenterJohns Hopkins School of MedicineBaltimoreMDUSA
| | - Xianzun Tao
- Department of Molecular and Cellular PharmacologyUniversity of Miami Miller School of MedicineMiamiFLUSA
| | - Alex R Khomutov
- Engelhardt Institute of Molecular BiologyRussian Academy of SciencesMoscowRussia
| | - R Grace Zhai
- Department of Molecular and Cellular PharmacologyUniversity of Miami Miller School of MedicineMiamiFLUSA
| | - Robert A Casero
- Sidney Kimmel Comprehensive Cancer CenterJohns Hopkins School of MedicineBaltimoreMDUSA
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3
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Stewart TRM, Foley JR, Holbert CE, Khomutov MA, Rastkari N, Tao X, Khomutov AR, Zhai RG, Casero RA. Difluoromethylornithine rebalances aberrant polyamine ratios in Snyder-Robinson syndrome: mechanism of action and therapeutic potential. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.30.534977. [PMID: 37034775 PMCID: PMC10081208 DOI: 10.1101/2023.03.30.534977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Snyder-Robinson Syndrome (SRS) is caused by mutations in the spermine synthase (SMS) gene, the enzyme product of which converts the polyamine spermidine into spermine. Affecting primarily males, common manifestations of SRS include intellectual disability, osteoporosis, hypotonic musculature, and seizures, along with other more variable symptoms. Currently, medical management focuses on treating these symptoms without addressing the underlying molecular cause of the disease. Reduced SMS catalytic activity in cells of SRS patients causes the accumulation of spermidine, while spermine levels are reduced. The resulting exaggeration in spermidine-to-spermine ratio is a biochemical hallmark of SRS that tends to correlate with symptom severity in the patient. Our studies aim to pharmacologically manipulate polyamine metabolism to correct this polyamine imbalance and investigate the potential of this approach as a therapeutic strategy for affected individuals. Here we report the use of difluoromethylornithine (DFMO; eflornithine), an FDA-approved inhibitor of polyamine biosynthesis, in re-establishing normal spermidine-to-spermine ratios in SRS patient cells. Through mechanistic studies, we demonstrate that, while reducing spermidine biosynthesis, DFMO also stimulates the conversion of existing spermidine into spermine in cell lines with hypomorphic variants of SMS. Further, DFMO treatment induces a compensatory uptake of exogenous polyamines, including spermine and spermine mimetics, cooperatively reducing spermidine and increasing spermine levels. In a Drosophila SRS model characterized by reduced lifespan, adding DFMO to the feed extended lifespan. As nearly all known SRS patient mutations are hypomorphic, these studies form a foundation for future translational studies with significant therapeutic potential.
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Michael J, VanSickle E, Vipond M, Dalman A, Prokop J, Schwartz CE, Rajasekaran S, Bachmann AS, Barth M, Prouteau C, Almagor Y, Berkun L, Alterescu G, Bupp CP. Two New Cases of Bachmann-Bupp Syndrome Identified through the International Center for Polyamine Disorders. Med Sci (Basel) 2023; 11:29. [PMID: 37092498 PMCID: PMC10123676 DOI: 10.3390/medsci11020029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 03/29/2023] [Accepted: 03/29/2023] [Indexed: 04/07/2023] Open
Abstract
Recent identification of four additional polyaminopathies, including Bachmann-Bupp syndrome, have benefited from previous research on Snyder-Robinson syndrome in order to advance from research to treatment more quickly. As a result of the discovery of these conditions, the potential for treatment within this pathway, and for other possible unidentified polyaminopathies, the International Center for Polyamine Disorders (ICPD) was created to help promote understanding of these conditions, research opportunities, and appropriate care for families. This case study provides insights from two new patients diagnosed with Bachmann-Bupp syndrome, further expanding our understanding of this ultra-rare condition, as well as a general discussion about other known polyaminopathies. This work also presents considerations for collaborative research efforts across these conditions, along with others that are likely to be identified in time, and outlines the role that the ICPD hopes to fill as more patients with these polyaminopathies continue to be identified and diagnosed.
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Affiliation(s)
- Julianne Michael
- Corewell Health and Helen DeVos Children’s Hospital, Grand Rapids, MI 49503, USA
- International Center for Polyamine Disorders, Grand Rapids, MI 49503, USA
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Elizabeth VanSickle
- Corewell Health and Helen DeVos Children’s Hospital, Grand Rapids, MI 49503, USA
- International Center for Polyamine Disorders, Grand Rapids, MI 49503, USA
| | - Marlie Vipond
- Corewell Health and Helen DeVos Children’s Hospital, Grand Rapids, MI 49503, USA
- International Center for Polyamine Disorders, Grand Rapids, MI 49503, USA
| | - Abby Dalman
- Corewell Health and Helen DeVos Children’s Hospital, Grand Rapids, MI 49503, USA
| | - Jeremy Prokop
- Corewell Health and Helen DeVos Children’s Hospital, Grand Rapids, MI 49503, USA
| | - Charles E. Schwartz
- International Center for Polyamine Disorders, Grand Rapids, MI 49503, USA
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Surender Rajasekaran
- Corewell Health and Helen DeVos Children’s Hospital, Grand Rapids, MI 49503, USA
- International Center for Polyamine Disorders, Grand Rapids, MI 49503, USA
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - André S. Bachmann
- International Center for Polyamine Disorders, Grand Rapids, MI 49503, USA
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Magalie Barth
- Department of Biochemistry and Genetics, Angers University Hospital Center, 49100 Angers, France
| | - Clément Prouteau
- Department of Biochemistry and Genetics, Angers University Hospital Center, 49100 Angers, France
| | | | - Lina Berkun
- Shaare Zedek Medical Center, Medical Genetics Institute, Jerusalem 9103102, Israel
| | - Gheona Alterescu
- Shaare Zedek Medical Center, Medical Genetics Institute, Jerusalem 9103102, Israel
| | - Caleb P. Bupp
- Corewell Health and Helen DeVos Children’s Hospital, Grand Rapids, MI 49503, USA
- International Center for Polyamine Disorders, Grand Rapids, MI 49503, USA
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
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5
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Colonna MB, Moss T, Mokashi S, Srikanth S, Jones JR, Foley JR, Skinner C, Lichty A, Kocur A, Wood T, Stewart TM, Casero Jr. RA, Flanagan-Steet H, Edison AS, Lyons MJ, Steet R. Functional assessment of homozygous ALDH18A1 variants reveals alterations in amino acid and antioxidant metabolism. Hum Mol Genet 2023; 32:732-744. [PMID: 36067040 PMCID: PMC9941824 DOI: 10.1093/hmg/ddac226] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 07/08/2022] [Accepted: 09/01/2022] [Indexed: 11/13/2022] Open
Abstract
Mono- and bi-allelic variants in ALDH18A1 cause a spectrum of human disorders associated with cutaneous and neurological findings that overlap with both cutis laxa and spastic paraplegia. ALDH18A1 encodes the bifunctional enzyme pyrroline-5-carboxylate synthetase (P5CS) that plays a role in the de novo biosynthesis of proline and ornithine. Here we characterize a previously unreported homozygous ALDH18A1 variant (p.Thr331Pro) in four affected probands from two unrelated families, and demonstrate broad-based alterations in amino acid and antioxidant metabolism. These four patients exhibit variable developmental delay, neurological deficits and loose skin. Functional characterization of the p.Thr331Pro variant demonstrated a lack of any impact on the steady-state level of the P5CS monomer or mitochondrial localization of the enzyme, but reduced incorporation of the monomer into P5CS oligomers. Using an unlabeled NMR-based metabolomics approach in patient fibroblasts and ALDH18A1-null human embryonic kidney cells expressing the variant P5CS, we identified reduced abundance of glutamate and several metabolites derived from glutamate, including proline and glutathione. Biosynthesis of the polyamine putrescine, derived from ornithine, was also decreased in patient fibroblasts, highlighting the functional consequence on another metabolic pathway involved in antioxidant responses in the cell. RNA sequencing of patient fibroblasts revealed transcript abundance changes in several metabolic and extracellular matrix-related genes, adding further insight into pathogenic processes associated with impaired P5CS function. Together these findings shed new light on amino acid and antioxidant pathways associated with ALDH18A1-related disorders, and underscore the value of metabolomic and transcriptomic profiling to discover new pathways that impact disease pathogenesis.
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Affiliation(s)
- Maxwell B Colonna
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - Tonya Moss
- Greenwood Genetic Center, Greenwood, SC 29646, USA
| | | | | | | | - Jackson R Foley
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine; Baltimore, MD 21287, USA
| | | | - Angie Lichty
- Greenwood Genetic Center, Greenwood, SC 29646, USA
| | | | - Tim Wood
- Department of Pathology and Laboratory Medicine, Children’s Hospital Colorado, Aurora, CO 80045, USA
| | - Tracy Murray Stewart
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine; Baltimore, MD 21287, USA
| | - Robert A Casero Jr.
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine; Baltimore, MD 21287, USA
| | | | - Arthur S Edison
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
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6
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Tao X, Zhu Y, Diaz-Perez Z, Yu SH, Foley JR, Stewart TM, Casero RA, Steet R, Zhai RG. Phenylbutyrate modulates polyamine acetylase and ameliorates Snyder-Robinson syndrome in a Drosophila model and patient cells. JCI Insight 2022; 7:e158457. [PMID: 35801587 PMCID: PMC9310527 DOI: 10.1172/jci.insight.158457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 05/20/2022] [Indexed: 11/26/2022] Open
Abstract
Polyamine dysregulation plays key roles in a broad range of human diseases from cancer to neurodegeneration. Snyder-Robinson syndrome (SRS) is the first known genetic disorder of the polyamine pathway, caused by X-linked recessive loss-of-function mutations in spermine synthase. In the Drosophila SRS model, altered spermidine/spermine balance has been associated with increased generation of ROS and aldehydes, consistent with elevated spermidine catabolism. These toxic byproducts cause mitochondrial and lysosomal dysfunction, which are also observed in cells from SRS patients. No efficient therapy is available. We explored the biochemical mechanism and discovered acetyl-CoA reduction and altered protein acetylation as potentially novel pathomechanisms of SRS. We repurposed the FDA-approved drug phenylbutyrate (PBA) to treat SRS using an in vivo Drosophila model and patient fibroblast cell models. PBA treatment significantly restored the function of mitochondria and autolysosomes and extended life span in vivo in the Drosophila SRS model. Treating fibroblasts of patients with SRS with PBA ameliorated autolysosome dysfunction. We further explored the mechanism of drug action and found that PBA downregulates the first and rate-limiting spermidine catabolic enzyme spermidine/spermine N1-acetyltransferase 1 (SAT1), reduces the production of toxic metabolites, and inhibits the reduction of the substrate acetyl-CoA. Taken together, we revealed PBA as a potential modulator of SAT1 and acetyl-CoA levels and propose PBA as a therapy for SRS and potentially other polyamine dysregulation-related diseases.
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Affiliation(s)
- Xianzun Tao
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Yi Zhu
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Zoraida Diaz-Perez
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Seok-Ho Yu
- JC Self Research Institute, Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - Jackson R. Foley
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Tracy Murray Stewart
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Robert A. Casero
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Richard Steet
- JC Self Research Institute, Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - R. Grace Zhai
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
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Marhabaie M, Hickey SE, Miller K, Grischow O, Schieffer KM, Franklin SJ, Gordon DM, Choi S, Mihalic Mosher T, White P, Koboldt DC, Wilson RK. Maternal mosaicism for a missense variant in the SMS gene that causes Snyder-Robinson syndrome. Cold Spring Harb Mol Case Stud 2021; 7:mcs.a006122. [PMID: 34667072 PMCID: PMC8751409 DOI: 10.1101/mcs.a006122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 09/30/2021] [Indexed: 11/25/2022] Open
Abstract
There is increasing recognition for the contribution of genetic mosaicism to human disease, particularly as high-throughput sequencing has enabled detection of sequence variants at very low allele frequencies. Here, we describe an infant male who presented at 9 mo of age with hypotonia, dysmorphic features, congenital heart disease, hyperinsulinemic hypoglycemia, hypothyroidism, and bilateral sensorineural hearing loss. Whole-genome sequencing of the proband and the parents uncovered an apparent de novo mutation in the X-linked SMS gene. SMS encodes spermine synthase, which catalyzes the production of spermine from spermidine. Inactivation of the SMS gene disrupts the spermidine/spermine ratio, resulting in Snyder–Robinson syndrome. The variant in our patient is absent from the gnomAD and ExAC databases and causes a missense change (p.Arg130Cys) predicted to be damaging by most in silico tools. Although Sanger sequencing confirmed the de novo status in our proband, polymerase chain reaction (PCR) and deep targeted resequencing to ∼84,000×–175,000× depth revealed that the variant is present in blood from the unaffected mother at ∼3% variant allele frequency. Our findings thus provided a long-sought diagnosis for the family while highlighting the role of parental mosaicism in severe genetic disorders.
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Affiliation(s)
- Mohammad Marhabaie
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Scott E Hickey
- Division of Genetic and Genomic Medicine at Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pediatrics at The Ohio State University College of Medicine, Columbus, Ohio 43210, USA
| | - Katherine Miller
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Olivia Grischow
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Kathleen M Schieffer
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Samuel J Franklin
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - David M Gordon
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Samantha Choi
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Theresa Mihalic Mosher
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Peter White
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pediatrics at The Ohio State University College of Medicine, Columbus, Ohio 43210, USA
| | - Daniel C Koboldt
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pediatrics at The Ohio State University College of Medicine, Columbus, Ohio 43210, USA
| | - Richard K Wilson
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pediatrics at The Ohio State University College of Medicine, Columbus, Ohio 43210, USA
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8
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Dontaine P, Kottos E, Dassonville M, Balasel O, Catros V, Soblet J, Perlot P, Vilain C. Digestive involvement in a severe form of Snyder-Robinson syndrome: Possible expansion of the phenotype. Eur J Med Genet 2020; 64:104097. [PMID: 33186760 DOI: 10.1016/j.ejmg.2020.104097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 10/23/2020] [Accepted: 11/04/2020] [Indexed: 11/30/2022]
Abstract
Snyder-Robinson syndrome (OMIM #309583) is a rare X-linked condition, caused by mutation in the SMS gene (MIM *300105), characterized by a wide spectrum of clinical signs including developmental delay, epilepsy, asthenic habitus, dysmorphism, osteopenia, and renal or genital anomalies. Here we describe two maternal half-brothers who both presented with severe neurodevelopmental delay, seizures, hearing loss, facial dysmorphism, renal and ophthalmologic anomalies, failure to thrive and premature death. A novel p.(Gly203Asp) variant was found at the hemizygous state in the two boys, and an elevated Spermidine/Spermine ratio confirmed the diagnosis of Snyder-Robinson syndrome. One of the brothers presented with gastrointestinal symptoms, with jejunal stenosis, enteral feeding intolerance, failure to thrive due to a dysfunctional gastrointestinal system, cholestasis and exocrine pancreatic insufficiency. Although more studies will be needed to understand its mechanisms, this observation lends further support to the possibility of severe digestive involvement in Snyder Robinson syndrome.
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Affiliation(s)
- Pauline Dontaine
- Department of Genetics, Hôpital Universitaire des Enfants Reine Fabiola, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium
| | - Elisa Kottos
- Department of Genetics, Hôpital Universitaire des Enfants Reine Fabiola, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium
| | - Martine Dassonville
- Department of Pediatric Surgery, Hôpital Universitaire des Enfants Reine Fabiola, Universite Libre de Bruxelles, Brussels, Belgium
| | - Ovidiu Balasel
- Department of Neonatalogy, Hôpital Universitaire des Enfants Reine Fabiola, Universite Libre de Bruxelles, Brussels, Belgium
| | - Véronique Catros
- Univ Rennes, Inserm, CHU Rennes, Institut NUMECAN (Nutrition Metabolisms and Cancer), CRB Santé Rennes, F-35000, Rennes, France
| | - Julie Soblet
- Department of Genetics, Hôpital Universitaire des Enfants Reine Fabiola, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium; Department of Genetics, Hôpital Erasme, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium; Interuniversity Institute of Bioinformatics in Brussels, Universite Libre de Bruxelles, Brussels, Belgium
| | - Pascale Perlot
- Department of Pediatrics, Hôpital Universitaire des Enfants Reine Fabiola, Universite Libre de Bruxelles, Brussels, Belgium
| | - Catheline Vilain
- Department of Genetics, Hôpital Universitaire des Enfants Reine Fabiola, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium; Department of Genetics, Hôpital Erasme, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium; Interuniversity Institute of Bioinformatics in Brussels, Universite Libre de Bruxelles, Brussels, Belgium.
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9
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Qazi TJ, Wu Q, Aierken A, Lu D, Bukhari I, Hussain HMJ, Yang J, Mir A, Qing H. Whole-exome sequencing identifies a novel mutation in spermine synthase gene (SMS) associated with Snyder-Robinson Syndrome. BMC MEDICAL GENETICS 2020; 21:168. [PMID: 32838743 PMCID: PMC7446199 DOI: 10.1186/s12881-020-01095-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/26/2020] [Indexed: 11/10/2022]
Abstract
BACKGROUND Loss of function mutations in the spermine synthase gene (SMS) have been reported to cause a rare X-linked intellectual disability known as Snyder-Robinson Syndrome (SRS). Besides intellectual disability, SRS is also characterized by reduced bone density, osteoporosis and facial dysmorphism. SRS phenotypes evolve with age from childhood to adulthood. METHODS Whole exome sequencing was performed to know the causative gene/pathogenic variant. Later we confirmed the pathogenic variant through Sanger sequencing. Furthermore, we also performed the mutational analysis through HOPE SERVER and SWISS-MODEL. Also, radiographs were also obtained for affected individual to confirm the disease features. RESULTS In this article, we report the first Pakistani family consisting of three patients with SRS and a novel missense pathogenic variant in the SMS gene (c.905 C > T p.(Ser302Leu)). In addition to the typical phenotypes, one patient presented with early-onset seizures. Clinical features, genetic and in-silico analysis linked the affected patients of the family with Snyder-Robinson and suggest that this novel mutation affects the spermine synthase activity. CONCLUSION A novel missense variant in the SMS, c.905C > T p. (Ser302Leu), causing Snyder- Robinson Syndrome (SRS) is reported in three members of Pakistani Family.
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Affiliation(s)
- Talal J Qazi
- Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Qiao Wu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China
| | - Ailikemu Aierken
- Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Daru Lu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China.,Chongqing Population and Family Planning, Science and Technology Research Institute, National Health and Family Planning Commission, Chongqing, China
| | - Ihtisham Bukhari
- Key Laboratory of Helicobacter pylori and Microbiota and GI Cancer in Henan Province, Marshall Medical Research Center of Zhengzhou University, The 5th affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Hafiz M J Hussain
- Department of Nephrology, Institute of Nephrology, Shanghai Ruijin Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
| | - Jingmin Yang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China.,Chongqing Population and Family Planning, Science and Technology Research Institute, National Health and Family Planning Commission, Chongqing, China.,Shanghai WeHealth Biomedical Technology Co., Ltd., Shanghai, China
| | - Asif Mir
- Department of Biological Sciences, FBAS, International Islamic University, Islamabad, Pakistan.
| | - Hong Qing
- Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, China.
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10
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Murray Stewart T, Khomutov M, Foley JR, Guo X, Holbert CE, Dunston TT, Schwartz CE, Gabrielson K, Khomutov A, Casero RA. ( R, R)-1,12-Dimethylspermine can mitigate abnormal spermidine accumulation in Snyder-Robinson syndrome. J Biol Chem 2020; 295:3247-3256. [PMID: 31996374 DOI: 10.1074/jbc.ra119.011572] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 01/21/2020] [Indexed: 11/06/2022] Open
Abstract
Snyder-Robinson syndrome (SRS) is an X-linked intellectual disability syndrome caused by a loss-of-function mutation in the spermine synthase (SMS) gene. Primarily affecting males, the main manifestations of SRS include osteoporosis, hypotonic stature, seizures, cognitive impairment, and developmental delay. Because there is no cure for SRS, treatment plans focus on alleviating symptoms rather than targeting the underlying causes. Biochemically, the cells of individuals with SRS accumulate excess spermidine, whereas spermine levels are reduced. We recently demonstrated that SRS patient-derived lymphoblastoid cells are capable of transporting exogenous spermine and its analogs into the cell and, in response, decreasing excess spermidine pools to normal levels. However, dietary supplementation of spermine does not appear to benefit SRS patients or mouse models. Here, we investigated the potential use of a metabolically stable spermine mimetic, (R,R)-1,12-dimethylspermine (Me2SPM), to reduce the intracellular spermidine pools of SRS patient-derived cells. Me2SPM can functionally substitute for the native polyamines in supporting cell growth while stimulating polyamine homeostatic control mechanisms. We found that both lymphoblasts and fibroblasts from SRS patients can accumulate Me2SPM, resulting in significantly decreased spermidine levels with no adverse effects on growth. Me2SPM administration to mice revealed that Me2SPM significantly decreases spermidine levels in multiple tissues. Importantly, Me2SPM was detectable in brain tissue, the organ most affected in SRS, and was associated with changes in polyamine metabolic enzymes. These findings indicate that the (R,R)-diastereomer of 1,12-Me2SPM represents a promising lead compound in developing a treatment aimed at targeting the molecular mechanisms underlying SRS pathology.
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Affiliation(s)
- Tracy Murray Stewart
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland 21287
| | - Maxim Khomutov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Jackson R Foley
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland 21287
| | - Xin Guo
- Department of Molecular and Comparative Pathobiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Cassandra E Holbert
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland 21287
| | - Tiffany T Dunston
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland 21287
| | | | - Kathleen Gabrielson
- Department of Molecular and Comparative Pathobiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Alexey Khomutov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Robert A Casero
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland 21287.
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11
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Polyamine Homeostasis in Snyder-Robinson Syndrome. Med Sci (Basel) 2018; 6:medsci6040112. [PMID: 30544565 PMCID: PMC6318755 DOI: 10.3390/medsci6040112] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 11/29/2018] [Accepted: 12/03/2018] [Indexed: 02/04/2023] Open
Abstract
Loss-of-function mutations of the spermine synthase gene (SMS) result in Snyder-Robinson Syndrome (SRS), a recessive X-linked syndrome characterized by intellectual disability, osteoporosis, hypotonia, speech abnormalities, kyphoscoliosis, and seizures. As SMS catalyzes the biosynthesis of the polyamine spermine from its precursor spermidine, SMS deficiency causes a lack of spermine with an accumulation of spermidine. As polyamines, spermine, and spermidine play essential cellular roles that require tight homeostatic control to ensure normal cell growth, differentiation, and survival. Using patient-derived lymphoblast cell lines, we sought to comprehensively investigate the effects of SMS deficiency on polyamine homeostatic mechanisms including polyamine biosynthetic and catabolic enzymes, derivatives of the natural polyamines, and polyamine transport activity. In addition to decreased spermine and increased spermidine in SRS cells, ornithine decarboxylase activity and its product putrescine were significantly decreased. Treatment of SRS cells with exogenous spermine revealed that polyamine transport was active, as the cells accumulated spermine, decreased their spermidine level, and established a spermidine-to-spermine ratio within the range of wildtype cells. SRS cells also demonstrated elevated levels of tissue transglutaminase, a change associated with certain neurodegenerative diseases. These studies form a basis for further investigations into the leading biochemical changes and properties of SMS-mutant cells that potentially represent therapeutic targets for the treatment of Snyder-Robinson Syndrome.
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12
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Starks R, Kirby P, Ciliberto M, Hefti M. Snyder-Robinson syndrome. AUTOPSY AND CASE REPORTS 2018; 8:e2018031. [PMID: 30237987 PMCID: PMC6140707 DOI: 10.4322/acr.2018.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 06/17/2018] [Indexed: 11/23/2022] Open
Abstract
Snyder-Robinson syndrome, also known as spermine synthase deficiency, is an X-linked intellectual disability syndrome (OMIM #390583). First described by Drs. Snyder and Robinson in 1969, this syndrome is characterized by an asthenic body habitus, facial dysmorphism, broad-based gait, and osteoporosis with frequent fractures. We report here a pediatric autopsy of a 4 year old male with a history of intellectual disability, gait abnormalities, multiple fractures, and seizures previously diagnosed with Snyder-Robinson syndrome with an SMS gene mutation (c.831G>T:p.L277F). The cause of death was hypoxic-ischemic encephalopathy secondary to prolonged seizure activity. Although Snyder-Robinson syndrome is rare, the need to recognize clinical findings in order to trigger genetic testing has likely resulted in under diagnosis.
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Affiliation(s)
- Rachel Starks
- University of Iowa Hospitals and Clinics, Department of Pathology. Iowa City, IA, United States of America
| | - Patricia Kirby
- University of Iowa Hospitals and Clinics, Department of Pathology. Iowa City, IA, United States of America
| | - Michael Ciliberto
- University of Iowa Hospitals and Clinics, Department of Pediatrics. Iowa City, IA, United States of America
| | - Marco Hefti
- University of Iowa Hospitals and Clinics, Department of Pathology. Iowa City, IA, United States of America
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13
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Abela L, Simmons L, Steindl K, Schmitt B, Mastrangelo M, Joset P, Papuc M, Sticht H, Baumer A, Crowther LM, Mathis D, Rauch A, Plecko B. N(8)-acetylspermidine as a potential plasma biomarker for Snyder-Robinson syndrome identified by clinical metabolomics. J Inherit Metab Dis 2016; 39:131-7. [PMID: 26174906 DOI: 10.1007/s10545-015-9876-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 06/16/2015] [Accepted: 06/16/2015] [Indexed: 11/26/2022]
Abstract
Clinical metabolomics has emerged as a powerful tool to study human metabolism in health and disease. Comparative statistical analysis of untargeted metabolic profiles can reveal perturbations of metabolite levels in diseases and thus has the potential to identify novel biomarkers. Here we have applied a simultaneous genetic-metabolomic approach in twin boys with epileptic encephalopathy of unclear etiology. Clinical exome sequencing identified a novel missense mutation in the spermine synthase gene (SMS) that causes Snyder-Robinson syndrome (SRS). Untargeted plasma metabolome analysis revealed significantly elevated levels of N(8)-acetylspermidine, a precursor derivative of spermine biosynthesis, as a potential novel plasma biomarker for SRS. This result was verified in a third patient with genetically confirmed SRS. This study illustrates the potential of metabolomics as a translational technique to support exome data on a functional and clinical level.
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Affiliation(s)
- Lucia Abela
- Division of Child Neurology, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Children's Research Centre, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
| | - Luke Simmons
- Division of Child Neurology, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Children's Research Centre, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
| | - Katharina Steindl
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Institute of Medical Genetics, University of Zurich, Wagistrasse 12, 8952, Schlieren, Switzerland
| | - Bernhard Schmitt
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Division of Epilepsy and Neurophysiology, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
| | - Massimo Mastrangelo
- Pediatric Neurology Unit, V. Buzzi Children's Hospital, ICP, Via Castelvetro 24, 20154, Milan, Italy
| | - Pascal Joset
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Institute of Medical Genetics, University of Zurich, Wagistrasse 12, 8952, Schlieren, Switzerland
| | - Mihaela Papuc
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Institute of Medical Genetics, University of Zurich, Wagistrasse 12, 8952, Schlieren, Switzerland
| | - Heinrich Sticht
- Institute for Biochemistry, University of Erlangen-Nuernberg, Fahrstrasse 17, 91054, Erlangen, Germany
| | - Alessandra Baumer
- Institute of Medical Genetics, University of Zurich, Wagistrasse 12, 8952, Schlieren, Switzerland
| | - Lisa M Crowther
- Division of Child Neurology, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Children's Research Centre, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
| | - Déborah Mathis
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
| | - Anita Rauch
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Institute of Medical Genetics, University of Zurich, Wagistrasse 12, 8952, Schlieren, Switzerland
| | - Barbara Plecko
- Division of Child Neurology, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland.
- Children's Research Centre, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland.
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland.
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14
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Albert JS, Bhattacharyya N, Wolfe LA, Bone WP, Maduro V, Accardi J, Adams DR, Schwartz CE, Norris J, Wood T, Gafni RI, Collins MT, Tosi LL, Markello TC, Gahl WA, Boerkoel CF. Impaired osteoblast and osteoclast function characterize the osteoporosis of Snyder - Robinson syndrome. Orphanet J Rare Dis 2015; 10:27. [PMID: 25888122 PMCID: PMC4428506 DOI: 10.1186/s13023-015-0235-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 01/28/2015] [Indexed: 11/25/2022] Open
Abstract
Background Snyder-Robinson Syndrome (SRS) is an X-linked intellectual disability disorder also characterized by osteoporosis, scoliosis, and dysmorphic facial features. It is caused by mutations in SMS, a ubiquitously expressed gene encoding the polyamine biosynthetic enzyme spermine synthase. We hypothesized that the tissue specificity of SRS arises from differential sensitivity to spermidine toxicity or spermine deficiency. Methods We performed detailed clinical, endocrine, histopathologic, and morphometric studies on two affected brothers with a spermine synthase loss of function mutation (NM_004595.4:c.443A > G, p.Gln148Arg). We also measured spermine and spermidine levels in cultured human bone marrow stromal cells (hBMSCs) and fibroblasts using the Biochrom 30 polyamine protocol and assessed the osteogenic potential of hBMSCs. Results In addition to the known tissue-specific features of SRS, the propositi manifested retinal pigmentary changes, recurrent episodes of hyper- and hypoglycemia, nephrocalcinosis, renal cysts, and frequent respiratory infections. Bone histopathology and morphometry identified a profound depletion of osteoblasts and osteoclasts, absence of a trabecular meshwork, a low bone volume and a thin cortex. Comparison of cultured fibroblasts from affected and unaffected individuals showed relatively small changes in polyamine content, whereas comparison of cultured osteoblasts identified marked differences in spermidine and spermine content. Osteogenic differentiation of the SRS-derived hBMSCs identified a severe deficiency of calcium phosphate mineralization. Conclusions Our findings support the hypothesis that cell specific alterations in polyamine metabolism contribute to the tissue specificity of SRS features, and that the low bone density arises from a failure of mineralization. Electronic supplementary material The online version of this article (doi:10.1186/s13023-015-0235-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jessica S Albert
- Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD, 20814, USA. .,Medical Genetics Branch, National Human Genome Research Institute, Bethesda, MD, USA.
| | - Nisan Bhattacharyya
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Disease Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Lynne A Wolfe
- Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD, 20814, USA. .,Medical Genetics Branch, National Human Genome Research Institute, Bethesda, MD, USA.
| | - William P Bone
- Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD, 20814, USA.
| | - Valerie Maduro
- Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD, 20814, USA.
| | - John Accardi
- Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD, 20814, USA.
| | - David R Adams
- Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD, 20814, USA. .,Medical Genetics Branch, National Human Genome Research Institute, Bethesda, MD, USA.
| | - Charles E Schwartz
- J.C. Self Research Institute, Greenwood Genetics Centre, Greenwood, SC, 29646, USA.
| | - Joy Norris
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Disease Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Tim Wood
- J.C. Self Research Institute, Greenwood Genetics Centre, Greenwood, SC, 29646, USA.
| | - Rachel I Gafni
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Disease Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Michael T Collins
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Disease Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Laura L Tosi
- George Washington University School of Medicine, Washington, DC, USA. .,Children's National Medical Center, Washington, DC, USA.
| | - Thomas C Markello
- Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD, 20814, USA. .,Medical Genetics Branch, National Human Genome Research Institute, Bethesda, MD, USA.
| | - William A Gahl
- Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD, 20814, USA. .,Medical Genetics Branch, National Human Genome Research Institute, Bethesda, MD, USA.
| | - Cornelius F Boerkoel
- Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD, 20814, USA.
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15
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Peron A, Spaccini L, Norris J, Bova SM, Selicorni A, Weber G, Wood T, Schwartz CE, Mastrangelo M. Snyder-Robinson syndrome: A novel nonsense mutation in spermine synthase and expansion of the phenotype. Am J Med Genet A 2013; 161A:2316-20. [DOI: 10.1002/ajmg.a.36116] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 05/27/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Angela Peron
- Clinical Genetics Service; V. Buzzi Children's Hospital; ICP Milan Italy
| | - Luigina Spaccini
- Clinical Genetics Service; V. Buzzi Children's Hospital; ICP Milan Italy
| | - Joy Norris
- JC Self Research Institute; Greenwood Genetic Center; Greenwood South Carolina
| | - Stefania M. Bova
- Pediatric Neurology Unit; V. Buzzi Children's Hospital; ICP Milan Italy
| | | | - Giovanna Weber
- Pediatrics Clinic; Vita-Salute San Raffaele University; Milan Italy
| | - Tim Wood
- JC Self Research Institute; Greenwood Genetic Center; Greenwood South Carolina
| | - Charles E. Schwartz
- JC Self Research Institute; Greenwood Genetic Center; Greenwood South Carolina
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16
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Zhang Z, Norris J, Kalscheuer V, Wood T, Wang L, Schwartz C, Alexov E, Van Esch H. A Y328C missense mutation in spermine synthase causes a mild form of Snyder-Robinson syndrome. Hum Mol Genet 2013; 22:3789-97. [PMID: 23696453 DOI: 10.1093/hmg/ddt229] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Snyder-Robinson syndrome (SRS, OMIM: 309583) is an X-linked intellectual disability (XLID) syndrome, characterized by a collection of clinical features including facial asymmetry, marfanoid habitus, hypertonia, osteoporosis and unsteady gait. It is caused by a significant decrease or loss of spermine synthase (SMS) activity. Here, we report a new missense mutation, p.Y328C (c.1084A>G), in SMS in a family with XLID. The affected males available for evaluation had mild ID, speech and global delay, an asthenic build, short stature with long fingers and mild kyphosis. The spermine/spermidine ratio in lymphoblasts was 0.53, significantly reduced compared with normal (1.87 average). Activity analysis of SMS in the index patient failed to detect any activity above background. In silico modeling demonstrated that the Y328C mutation has a significant effect on SMS stability, resulting in decreased folding free energy and larger structural fluctuations compared with those of wild-type SMS. The loss of activity was attributed to the increase in conformational dynamics in the mutant which affects the active site geometry, rather than preventing dimer formation. Taken together, the biochemical and in silico studies confirm the p.Y328C mutation in SMS is responsible for the patients having a mild form of SRS and reveal yet another molecular mechanism resulting in a non-functional SMS causing SRS.
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Affiliation(s)
- Zhe Zhang
- Computational Biophysics and Bioinformatics, Department of Physics, Clemson University, Clemson, SC 29634, USA
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17
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Diagnostic screening for spermine synthase deficiency by liquid chromatography tandem mass spectrometry. Clin Chim Acta 2011; 412:655-60. [DOI: 10.1016/j.cca.2010.12.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 12/24/2010] [Accepted: 12/27/2010] [Indexed: 10/18/2022]
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18
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Schwartz CE, Wang X, Stevenson RE, Pegg AE. Spermine synthase deficiency resulting in X-linked intellectual disability (Snyder-Robinson syndrome). Methods Mol Biol 2011; 720:437-445. [PMID: 21318891 DOI: 10.1007/978-1-61779-034-8_28] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Polyamines, small positively charged molecules, are vital for cell proliferation and differentiation. They are found ubiquitously in eukaryotic cells. Additionally, they interact with a wide range of other molecules and some membrane associated receptors. Polyamines, spermidine and spermine, are synthesized by two aminopropyltransferases, spermidine synthase and spermine synthase. Recently, mutations in the latter enzyme have been shown to be responsible for an X-linked intellectual disability condition known as Snyder-Robinson syndrome. Spermine synthase deficiency is thus far the only known polyamine deficiency syndrome in humans.
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Affiliation(s)
- Charles E Schwartz
- Greenwood Genetic Center, J.C. Self Research Institute, Greenwood, SC, USA.
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19
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Spermine synthase activity affects the content of decarboxylated S-adenosylmethionine. Biochem J 2010; 433:139-44. [DOI: 10.1042/bj20101228] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
dcAdoMet (decarboxylated S-adenosylmethionine) is an essential intermediate in the synthesis of polyamines. Its content is normally very low, amounting to less than 5% of that of S-adenosylmethionine itself. It was found that in mice lacking spermine synthase there was a large increase in dcAdoMet and that overexpression of spermine synthase reduced the amount of this nucleoside. There was also an increase in dcAdoMet in cells derived from patients with Snyder–Robinson syndrome, a rare X-linked recessive human disease caused by SMS gene mutations that greatly reduce the content of spermine synthase. These results suggest that there is an inverse relationship between the amount of spermine synthase protein and the content of dcAdoMet and raise the possibility that some of the abnormalities seen in mammals deficient in spermine synthase might be due to changes in dcAdoMet pools.
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20
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du Souich C, Chou A, Yin J, Oh T, Nelson TN, Hurlburt J, Arbour L, Friedlander R, McGillivray BC, Tyshchenko N, Rump A, Poskitt KJ, Demos MK, Van Allen MI, Boerkoel CF. Characterization of a new X-linked mental retardation syndrome with microcephaly, cortical malformation, and thin habitus. Am J Med Genet A 2010; 149A:2469-78. [PMID: 19842190 DOI: 10.1002/ajmg.a.33071] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
X-linked mental retardation (XLMR) affects 1-2/1,000 males and accounts for approximately 10% of all mental retardation (MR). We have ascertained a syndromic form of XLMR segregating within a five-generation family with seven affected males. Prominent characteristics include mild to severe MR, cortical malformation, microcephaly, seizures, thin build with distinct facial features including a long and thin face, epicanthic folds, almond-shaped eyes, upslanting palpebral fissures and micrognathia and behavioral problems. Carrier females have normal physical appearance and intelligence. This combination of features is unreported and distinct from Lujan-Fryns syndrome, Snyder-Robinson syndrome, and zinc finger DHHC domain-containing 9-associated MR. We propose the name of this new syndrome to be CK syndrome.
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21
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Becerra-Solano LE, Butler J, Castañeda-Cisneros G, McCloskey DE, Wang X, Pegg AE, Schwartz CE, Sánchez-Corona J, García-Ortiz JE. A missense mutation, p.V132G, in the X-linked spermine synthase gene (SMS) causes Snyder-Robinson syndrome. Am J Med Genet A 2009; 149A:328-35. [PMID: 19206178 DOI: 10.1002/ajmg.a.32641] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Snyder-Robinson syndrome (SRS, OMIM 309583) is a rare X-linked syndrome characterized by mental retardation, marfanoid habitus, skeletal defects, osteoporosis, and facial asymmetry. Linkage analysis localized the related gene to Xp21.3-p22.12, and a G-to-A transition at point +5 of intron 4 of the spermine synthase gene, which caused truncation of the SMS protein and loss of enzyme activity, was identified in the original family. Here we describe another family with Snyder-Robinson syndrome in two Mexican brothers and a novel mutation (c.496T>G) in the exon 5 of the SMS gene confirming its involvement in this rare X-linked mental retardation syndrome.
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Affiliation(s)
- L E Becerra-Solano
- División de Genética, Centro de Investigación Biomédica de Occidente, CMNO-IMSS, Guadalajara, Mexico
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22
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The impact of spermine synthase (SMS) mutations on brain morphology. Neurogenetics 2009; 10:299-305. [PMID: 19277733 DOI: 10.1007/s10048-009-0184-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Accepted: 02/23/2009] [Indexed: 10/21/2022]
Abstract
Snyder-Robinson syndrome (SRS) is a form of X-linked mental retardation resulting from mutations in spermine synthase (SMS), which impact neurodevelopment and cognitive outcome. We obtained cerebral, cerebellum, hippocampus, and red nucleus volumes from two males with SRS and 24 age- and gender-matched typically developing controls using volumetric neuroimaging analyses. Total brain volume was enlarged in males with SRS while cerebellum, hippocampus, and red nucleus volumes tended to be reduced compared to controls. Mutations of the X chromosome may modulate the risk for mental retardation through altered early neurodevelopment, disruption in receptor function, and ongoing neural organization and plasticity. Disruption of SMS function may negatively affect regional brain volumes that subserve cognitive and motor abilities. This research provides valuable insight into the effects of polyamine function on brain development.
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23
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Rogers RC, Stevenson RE, Simensen RJ, Holden KR, Schwartz CE. Finding new etiologies of mental retardation and hypotonia: X marks the spot. Dev Med Child Neurol 2008; 50:104-11. [PMID: 18190539 DOI: 10.1111/j.1469-8749.2007.02022.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Mental retardation (MR) and hypotonia occur together frequently and have a heterogeneous etiology. Molecular and clinical studies have led to the recent discovery of genes on the X chromosome that may be associated with syndromal forms of X-linked MR (XLMR). These disorders manifest additional neurological and somatic features that are helpful in establishing a specific diagnosis and etiology. This article provides an overview of MR and its association with hypotonia, with a review of five 'new' XLMR-hypotonia syndromes.
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Cason AL, Ikeguchi Y, Skinner C, Wood TC, Holden KR, Lubs HA, Martinez F, Simensen RJ, Stevenson RE, Pegg AE, Schwartz CE. X-linked spermine synthase gene (SMS) defect: the first polyamine deficiency syndrome. Eur J Hum Genet 2004; 11:937-44. [PMID: 14508504 DOI: 10.1038/sj.ejhg.5201072] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Polyamines (putrescine, spermidine, spermine) are ubiquitous, simple molecules that interact with a variety of other molecules in the cell, including nucleic acids, phospholipids and proteins. Various studies indicate that polyamines are essential for normal cell growth and differentiation. Furthermore, these molecules, especially spermine, have been shown to modulate ion channel activities of certain cells. Nonetheless, little is known about the specific cellular functions of these compounds, and extensive laboratory investigations have failed to identify a heritable condition in humans in which polyamine synthesis is perturbed. We report the first polyamine deficiency syndrome caused by a defect in spermine synthase (SMS). The defect results from a splice mutation, and is associated with the Snyder-Robinson syndrome (SRS, OMIM_309583), an X-linked mental retardation disorder. The affected males have mild-to-moderate mental retardation (MR), hypotonia, cerebellar circuitry dysfunction, facial asymmetry, thin habitus, osteoporosis, kyphoscoliosis, decreased activity of SMS, correspondingly low levels of intracellular spermine in lymphocytes and fibroblasts, and elevated spermidine/spermine ratios. The clinical features observed in SRS are consistent with cerebellar dysfunction and a defective functioning of red nucleus neurons, which, at least in rats, contain high levels of spermine. Additionally, the presence of MR reflects a role for spermine in cognitive function, possibly by spermine's ability to function as an 'intrinsic gateway' molecule for inward rectifier K(+) channels.
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Affiliation(s)
- A Lauren Cason
- 1J.C. Self Research Institute, Greenwood Genetic Center, 1 Gregor Mendel Circle, Greenwood, SC 29646, USA
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Turner G, Gedeon A, Kerr B, Bennett R, Mulley J, Partington M. Syndromic form of X-linked mental retardation with marked hypotonia in early life, severe mental handicap, and difficult adult behavior maps to Xp22. Am J Med Genet A 2003; 117A:245-50. [PMID: 12599187 DOI: 10.1002/ajmg.a.10005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
An X-linked recessive syndromic form of mental retardation is described in a family in which 10 males in four generations were affected. The main manifestations were severe to profound intellectual disability, muscular hypotonia in childhood, delayed walking, and difficult, aggressive behavior. There was a moderate reduction both in occipitofrontal circumference (OFC) and height and a similar facial appearance, triangular in shape with a high forehead, prominent ears, and a small pointed chin. Linkage analysis located the gene at Xp22 with maximum lod scores of 4.8 at theta = 0.0 for markers mapping between the closest recombination points at DXS7104 and DXS418. The physical length of this region is approximately 6 Mb. Mutations in the GRPR gene and M6b genes were excluded by sequence analysis. Nearby genes in which mutations are known to be associated with mental retardation (RPS6KA3, STK9, and VCXA, B and C), were excluded by position.
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Affiliation(s)
- Gillian Turner
- Hunter Genetics, University of Newcastle, PO Box 84, Waratah, New South Wales 2298, Australia.
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Yang J, Kiefer S, Rauchman M. Characterization of the gene encoding mouse retinoblastoma binding protein-7, a component of chromatin-remodeling complexes. Genomics 2002; 80:407-15. [PMID: 12376095 DOI: 10.1006/geno.2002.6844] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
RBBP7 is a highly conserved WD-repeat protein that interacts with histone deacetylases and is a component of several co-repressor complexes. The mouse gene Rbbp7 spans approximately 20 kb, consists of at least 12 exons, and contains a C/T polymorphism in the 3' splice acceptor region of intron 3. We found that Rbbp7 contains a TATA-less promoter with multiple transcription initiation sites. In transient transfection assays, we identified potential positive regulatory elements upstream of the proximal promoter at -668 to -1710. RBBP7 protein is detectable from at least day 9.5 of embryogenesis and is strongly expressed in the developing kidney and brain. Consistent with its association with co-repressor complexes, we demonstrate that RBBP7 represses the c-FOS transactivation domain in response to mitogen stimulation. We have also excluded human RBBP7 as a candidate gene in six patients that exhibit X-linked mental retardation, a heterogeneous developmental disorder that has been linked in some cases to mutations in genes involved in chromatin remodeling.
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Affiliation(s)
- Jing Yang
- Renal Division, Washington University School of Medicine, Box 8126, 660 S. Euclid Ave. St. Louis, Missouri 63110, USA
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Bruyere H, Lewis S, Wood S, MacLeod PJ, Langlois S. Confirmation of linkage in X-linked infantile spasms (West syndrome) and refinement of the disease locus to Xp21.3-Xp22.1. Clin Genet 1999; 55:173-81. [PMID: 10334471 DOI: 10.1034/j.1399-0004.1999.550305.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The syndrome of infantile spasms, hypsarrhythmia, and mental retardation (West syndrome) is a classical form of epilepsy, occurring in early infancy, which is etiologically heterogeneous. In rare families, West syndrome is an X-linked recessive condition, mapped to Xp11.4-Xpter (MIM 308350). We have identified a multi-generation family from Western Canada with this rare syndrome of infantile spasms, seen exclusively in male offspring from asymptomatic mothers, thereby confirming segregation as an X-linked recessive trait. Using highly polymorphic microsatellite CA-repeat probes evenly distributed over the entire X chromosome, linkage to markers DXS7110, DXS989, DXS1202, and DXS7106 was confirmed, with a maximum LOD score of 3.97 at a theta of 0.0. The identification of key recombinants refined the disease-containing interval between markers DXS1226 and the adrenal hypoplasia locus (AHC). This now maps the X-linked infantile spasms gene locus to chromosome Xp21.3-Xp22.1 and refines the interval containing the candidate gene to 7.0 cM. Furthermore, this interval overlaps several loci previously linked with either syndromic or non-syndromic X-linked mental retardation (XLMR), including one recognized locus implicated in neuroaxonal processing (radixin, RDXP2). Collectively, these studies lend strong support for the presence of one or more genes intrinsic to brain development and function, occurring within the critical interval defined between Xp21.3-Xp22.1.
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Affiliation(s)
- H Bruyere
- Department of Medical Genetics, Children's and Women's Health Center of British Columbia and the University of British Columbia, Vancouver, Canada
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29
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Stevenson RE, Arena JF, Ouzts E, Gibson A, Shokeir MH, Vnencak-Jones C, Lubs HA, May M, Schwartz CE. Renpenning syndrome maps to Xp11. Am J Hum Genet 1998; 62:1092-101. [PMID: 9545405 PMCID: PMC1377092 DOI: 10.1086/301835] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Mutations in genes on the X chromosome are believed to be responsible for the excess of males among individuals with mental retardation. Such genes are numerous, certainly >100, and cause both syndromal and nonsyndromal types of mental retardation. Clinical and molecular studies have been conducted on the Mennonite family with X-linked mental retardation (XLMR) reported, in 1962, by Renpenning et al. The clinical phenotype includes severe mental retardation, microcephaly, up-slanting palpebral fissures, small testes, and stature shorter than that of nonaffected males. Major malformations, neuromuscular abnormalities, and behavioral disturbances were not seen. Longevity is not impaired. Carrier females do not show heterozygote manifestations. The syndrome maps to Xp11.2-p11.4, with a maximum LOD score of 3.21 (recombination fraction 0) for markers between DXS1039 and DXS1068. Renpenning syndrome (also known as "MRXS8"; gene RENS1, MIM 309500) shares phenotypic manifestations with several other XLMR syndromes, notably the Sutherland-Haan syndrome. In none of these entities has the responsible gene been isolated; hence, the possibility that two or more of them may be allelic cannot be excluded at present.
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Plenge RM, Hendrich BD, Schwartz C, Arena JF, Naumova A, Sapienza C, Winter RM, Willard HF. A promoter mutation in the XIST gene in two unrelated families with skewed X-chromosome inactivation. Nat Genet 1997; 17:353-6. [PMID: 9354806 DOI: 10.1038/ng1197-353] [Citation(s) in RCA: 197] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
X-chromosome inactivation is the process by which a cell recognizes the presence of two copies of an X chromosome early in the development of XX embryos and chooses one to be active and one to be inactive. Although it is commonly believed that the initiation of X inactivation is random, with an equal probability (50:50) that either X chromosome will be the inactive X in a given cell, significant variation in the proportion of cells with either X inactive is observed both in mice heterozygous for alleles at the Xce locus and among normal human females in the population. Families in which multiple females demonstrate extremely skewed inactivation patterns that are otherwise quite rare in the general population are thought to reflect possible genetic influences on the X-inactivation process. Here we report a rare cytosine to guanine mutation in the XIST minimal promoter that underlies both epigenetic and functional differences between the two X chromosomes in nine females from two unrelated families. All females demonstrate preferential inactivation of the X chromosome carrying the mutation, suggesting that there is an association between alterations in the regulation of XIST expression and X-chromosome inactivation.
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Affiliation(s)
- R M Plenge
- Department of Genetics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
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Toutain A, Ayrault AD, Moraine C. Mental retardation in Nance-Horan syndrome: clinical and neuropsychological assessment in four families. AMERICAN JOURNAL OF MEDICAL GENETICS 1997; 71:305-14. [PMID: 9268101 DOI: 10.1002/(sici)1096-8628(19970822)71:3<305::aid-ajmg11>3.0.co;2-o] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Nance-Horan syndrome (NHS) is a rare X-linked condition comprising congenital cataract with microcornea, distinctive dental, and evocative facial anomalies. Intellectual handicap was mentioned in seven published NHS patients. We performed a clinical study focused on psychomotor development, intellectual abilities, and behavior in 13 affected males in four NHS families, and present the results of a neuropsychological evaluation in 7 of them. Our study confirms that mental retardation (MR) can be a major component of the NHS. Combining our data with those from the literature leads to a frequency of MR in NHS of around 30%. In most cases, MR is mild or moderate (80%) and not associated with motor delay. Conversely, a profound mental handicap associated with autistic traits may be observed. MR has intra- and inter-familial variability but does not appear to be expressed in carriers. Awareness of MR in NHS may be of importance in the management of the patients, especially in terms of education. Cloning and characterization of the gene and analysis of mutations will be an important step towards understanding the molecular basis of mental deficiency in NHS, and in delineation from the other XLMR conditions at Xp22.
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Affiliation(s)
- A Toutain
- Service de Génétique, Hôpital Bretonneau, Centre Hospitalo-Universitaire, Tours, France
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Strain L, Wright AF, Bonthron DT. Fried syndrome is a distinct X linked mental retardation syndrome mapping to Xp22. J Med Genet 1997; 34:535-40. [PMID: 9222959 PMCID: PMC1050991 DOI: 10.1136/jmg.34.7.535] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In 1972, Fried described a large Scottish family affected by X linked mental retardation (XLMR), hydrocephalus, and mild facial dysmorphism. The phenotype has considerable similarity to the MASA syndrome, which results from mutations of the L1CAM gene in Xq28, and this family has since been assumed to be an example of this condition. We have reinvestigated the family for linkage to X chromosome markers, and obtained additional clinical information on surviving affected subjects. The phenotype in these patients has evolved into a distinctive syndrome, with severe mental retardation (MR), spastic diplegia, ventricular dilatation, and calcification of the basal ganglia. Linkage to Xq28 markers has been excluded, suggesting that Fried syndrome is not allelic with MASA syndrome. Two point and multipoint linkage analysis indicates that the gene for this condition lies within the interval KAL-DXS989 in Xp22. We propose the designation Fried syndrome to emphasise the disorder's distinctive phenotype.
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Affiliation(s)
- L Strain
- University of Edinburgh Human Genetics Unit, Western General Hospital, UK
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33
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Abstract
A current list of all known forms of X-linked mental retardation (XLMR) and a slightly revised classification are presented. The number of known disorders has not increased because 6 disorders have been combined based on new molecular data or on clinical grounds and only 6 newly described XLMR disorders have been reported. Of the current 105 XLMR disorders, 34 have been mapped, and 18 disorders and 1 nonspecific XLMR (FRAXE) have been cloned. The number of families with nonspecific XLMR with a LOD score of > or = 2.0 has more than doubled, with 42 (including FRAXE) now being known. a summary of the localization of presumed nonspecific mental retardation (MR) genes from well-studied X-chromosomal translocations and deletions is also included. Only 10-12 nonoverlapping loci are required to explain all localizations of nonspecific MR from both approaches. These new trends mark the beginning of a significantly improved understanding of the role of genes on the X chromosome in producing MR. Continued close collaboration between clinical and molecular investigators will be required to complete the process.
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Affiliation(s)
- H A Lubs
- Department of Medical Genetics, University Hospital of Tromsø, Norway
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