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AAV2-hCHM Subretinal Delivery to the Macula in Choroideremia: Two Year Interim Results of an Ongoing Phase I/II Gene Therapy Trial. Ophthalmology 2022; 129:1177-1191. [PMID: 35714735 DOI: 10.1016/j.ophtha.2022.06.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 06/03/2022] [Accepted: 06/07/2022] [Indexed: 11/22/2022] Open
Abstract
PURPOSE To assess the safety of the subretinal delivery of a recombinant adeno-associated virus serotype 2 (AAV2) vector carrying a human CHM-encoding cDNA in choroideremia (CHM). DESIGN Prospective, open-label, non-randomized, dose-escalation, phase 1/2 clinical trial. SUBJECTS, PARTICIPANTS, AND/OR CONTROLS Fifteen CHM patients (ages 20-57 years at dosing). METHODS, INTERVENTION, OR TESTING Patients received uniocular subfoveal injections of low dose (up to 5x1010 vector genome (vg) per eye, n=5) or high dose (up to 1x1011 vg per eye, n=10) AAV2-hCHM. Patients were evaluated pre- and post-operatively for two years with ophthalmic examinations, multimodal retinal imaging and psychophysical testing. MAIN OUTCOME Measures: visual acuity (VA), perimetry (10-2 protocol), spectral-domain optical coherence tomography (SD-OCT) and short-wavelength fundus autofluorescence (SW-FAF). RESULTS We detected no vector-related or systemic toxicities. VA returned to within 15 letters of baseline in all but two patients (one developed acute foveal thinning, another patient, a macular hole); the rest showed no gross changes in foveal structure at two years. There were no significant differences between intervention and control eyes in mean light-adapted sensitivity by perimetry, or in the lateral extent of retinal pigment epithelium (RPE) relative preservation by SD-OCT and SW-FAF. Microperimetry showed non-significant (<3SD of the intervisit variability) gains in sensitivity in some locations and participants in the intervention eye. There were no obvious dose-dependent relationships. CONCLUSIONS VA was within 15 letters of baseline after the subfoveal AAV2-hCHM injections in 13/15 (87%) of the patients. Acute foveal thinning with unchanged perifoveal function in one patient and macular hole in a second suggests foveal vulnerability to the subretinal injections. Longer observation intervals will help establish the significance of the minor differences in sensitivities and rate of disease progression observed between intervention and control eyes.
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Hayashi T, Kameya S, Mizobuchi K, Kubota D, Kikuchi S, Yoshitake K, Mizota A, Murakami A, Iwata T, Nakano T. Genetic defects of CHM and visual acuity outcome in 24 choroideremia patients from 16 Japanese families. Sci Rep 2020; 10:15883. [PMID: 32985515 PMCID: PMC7522719 DOI: 10.1038/s41598-020-72623-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 09/02/2020] [Indexed: 11/15/2022] Open
Abstract
Choroideremia (CHM) is an incurable progressive chorioretinal dystrophy. Little is known about the natural disease course of visual acuity in the Japanese population. We aimed to investigate the genetic spectrum of the CHM gene and visual acuity outcomes in 24 CHM patients from 16 Japanese families. We measured decimal best-corrected visual acuity (BCVA) at presentation and follow-up, converted to logMAR units for statistical analysis. Sanger and/or whole-exome sequencing were performed to identify pathogenic CHM variants/deletions. The median age at presentation was 37.0 years (range, 5–76 years). The mean follow-up interval was 8.2 years. BCVA of the better-seeing eye at presentation was significantly worsened with increasing age (r = 0.515, p < 0.01), with a high rate of BCVA decline in patients > 40 years old. A Kaplan–Meier survival curve suggested that a BCVA of Snellen equivalent 20/40 at follow-up remains until the fifties. Fourteen pathogenic variants, 6 of which were novel [c.49 + 5G > A, c.116 + 5G > A, p.(Gly176Glu, Glu177Ter), p.Tyr531Ter, an exon 2 deletion, and a 5.0-Mb deletion], were identified in 15 families. No variant was found in one family only. Our BCVA outcome data are useful for predicting visual prognosis and determining the timing of intervention in Japanese patients with CHM variants.
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Affiliation(s)
- Takaaki Hayashi
- Department of Ophthalmology, Katsushika Medical Center, The Jikei University School of Medicine, 6-41-2 Aoto, Katsushika-ku, Tokyo, 125-8506, Japan. .,Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan.
| | - Shuhei Kameya
- Department of Ophthalmology, Nippon Medical School, Chiba Hokusoh Hospital, Chiba, Japan
| | - Kei Mizobuchi
- Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan
| | - Daiki Kubota
- Department of Ophthalmology, Nippon Medical School, Chiba Hokusoh Hospital, Chiba, Japan
| | - Sachiko Kikuchi
- Department of Ophthalmology, Nippon Medical School, Chiba Hokusoh Hospital, Chiba, Japan
| | - Kazutoshi Yoshitake
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization, Tokyo Medical Center, Tokyo, Japan
| | - Atsushi Mizota
- Department of Ophthalmology, Teikyo University School of Medicine, Tokyo, Japan
| | - Akira Murakami
- Department of Ophthalmology, Juntendo University, Faculty of Medicine, Tokyo, Japan
| | - Takeshi Iwata
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization, Tokyo Medical Center, Tokyo, Japan
| | - Tadashi Nakano
- Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan
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Silson EH, Aleman TS, Willett A, Serrano LW, Pearson DJ, Rauschecker AM, Maguire AM, Baker CI, Bennett J, Ashtari M. Comparing Clinical Perimetry and Population Receptive Field Measures in Patients with Choroideremia. Invest Ophthalmol Vis Sci 2019; 59:3249-3258. [PMID: 29971442 PMCID: PMC6110169 DOI: 10.1167/iovs.18-23929] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Purpose Choroideremia (CHM) is an X-linked recessive form of hereditary retinal degeneration, which, at advanced stages, leaves only small central islands of preserved retinal tissue. Unlike many other retinal diseases, the spared tissue in CHM supports excellent central vision and stable fixation. Such spared topography in CHM presents an ideal platform to explore the relationship between preserved central retinal structure and the retinotopic organization of visual cortex by using functional magnetic resonance imaging (fMRI). Methods fMRI was conducted in four participants with CHM and four healthy control participants while they viewed drifting contrast pattern stimuli monocularly. A single ∼3-minute fMRI run was collected for each eye separately. fMRI data were analyzed using the population receptive field (pRF) modeling approach. Participants also underwent ophthalmic evaluations of visual acuity and static automatic perimetry. Results The spatial distribution and strength of pRF estimates correlated positively and significantly with clinical outcome measures in most participants with CHM. Importantly, the positive relationship between clinical and pRF measurements increased with increasing disease progression. A less consistent relationship was observed for control participants. Conclusions Although reflecting only a small sample size, clinical evaluations of visual function in participants with CHM were well characterized by the spatial distribution and strength of pRF estimates by using a single ∼3-minute fMRI experiment. fMRI data analyzed with pRF modeling may be an efficient and objective outcome measure to complement current ophthalmic evaluations. Specifically, pRF modeling may be a feasible approach for evaluating the impact of interventions to restore visual function.
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Affiliation(s)
- Edward H Silson
- Section on Learning and Plasticity, Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, United States
| | - Tomas S Aleman
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), University of Pennsylvania, Philadelphia, Pennsylvania, United States.,F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Aimee Willett
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Leona W Serrano
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), University of Pennsylvania, Philadelphia, Pennsylvania, United States.,F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Denise J Pearson
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), University of Pennsylvania, Philadelphia, Pennsylvania, United States.,F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Andreas M Rauschecker
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Albert M Maguire
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), University of Pennsylvania, Philadelphia, Pennsylvania, United States.,F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Chris I Baker
- Section on Learning and Plasticity, Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, United States
| | - Jean Bennett
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), University of Pennsylvania, Philadelphia, Pennsylvania, United States.,F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Manzar Ashtari
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), University of Pennsylvania, Philadelphia, Pennsylvania, United States.,F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States.,Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
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Natural History of the Central Structural Abnormalities in Choroideremia: A Prospective Cross-Sectional Study. Ophthalmology 2016; 124:359-373. [PMID: 27986385 DOI: 10.1016/j.ophtha.2016.10.022] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 10/17/2016] [Accepted: 10/24/2016] [Indexed: 01/08/2023] Open
Abstract
PURPOSE To describe in detail the central retinal structure of a large group of patients with choroideremia (CHM). DESIGN A prospective, cross-sectional, descriptive study. PARTICIPANTS Patients (n = 97, age 6-71 years) with CHM and subjects with normal vision (n = 44; ages 10-50 years) were included. METHODS Subjects were examined with spectral-domain optical coherence tomography (SD OCT) and near-infrared reflectance imaging. Visual acuity (VA) was measured during their encounter or obtained from recent ophthalmic examinations. Visual thresholds were measured in a subset of patients (n = 24) with automated static perimetry within the central regions (±15°) examined with SD OCT. MAIN OUTCOME MEASURES Visual acuity and visual thresholds; total nuclear layer, inner nuclear layer (INL), and outer nuclear layer (ONL) thicknesses; and horizontal extent of the ONL and the photoreceptor outer segment (POS) interdigitation zone (IZ). RESULTS Earliest abnormalities in regions with normally appearing retinal pigment epithelium (RPE) were the loss of the POS and ellipsoid zone associated with rod dysfunction. Transition zones (TZs) from relatively preserved retina to severe ONL thinning and inner retinal thickening moved centripetally with age. Most patients (88%) retained VAs better than 20/40 until their fifth decade of life. The VA decline coincided with migration of the TZ near the foveal center. There were outer retinal tubulations in degenerated, nonatrophic retina in the majority (69%) of patients. In general, RPE abnormalities paralleled photoreceptor degeneration, although there were regions with detectable but abnormally thin ONL co-localizing with severe RPE depigmentation and choroidal thinning. CONCLUSIONS Abnormalities of the POS and rod dysfunction are the earliest central abnormalities observed in CHM. Foveal function is relatively preserved until the fifth decade of life. Migration of the TZs to the foveal center with foveal thinning and structural disorganization heralded central VA loss. The relationships established may help outline the eligibility criteria and outcome measures for clinical trials for CHM.
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Freund PR, Sergeev YV, MacDonald IM. Analysis of a large choroideremia dataset does not suggest a preference for inclusion of certain genotypes in future trials of gene therapy. Mol Genet Genomic Med 2016; 4:344-58. [PMID: 27247961 PMCID: PMC4867567 DOI: 10.1002/mgg3.208] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 01/16/2016] [Accepted: 01/20/2016] [Indexed: 11/17/2022] Open
Abstract
Background Choroideremia (CHM) is an X‐linked degeneration of the retinal pigment epithelium, photoreceptors, and choroid, which causes nyctalopia and progressive constriction of visual fields leading to blindness. The CHM gene encodes Rab escort protein 1 (REP‐1). In this work, we reviewed the phenotypes and genotypes of affected males with the purpose of understanding the functional effects of CHM mutations and their relationship with the phenotypes. Methods A retrospective review of 128 affected males was performed analyzing the onset of symptoms, visual acuity, and visual fields with respect to their mutations in the CHM gene. Results In rank order, reflecting data from this report, the most common mutations found in the CHM gene were nonsense mutations (41%), exon deletions (37%), and splice sites (14%) associated with a loss of functional protein. In the pool of 106 CHM mutations, we discovered four novel missense mutations (c.238C>T; p.L80F, c.819G>T; p.Q273H, c.1327A>G; p.M443V, and c.1370C>T; p.L457P) predicted to be severe changes affecting protein stability and folding with the effect similar to that of other types of mutations. No significant genotype–phenotype correlation was found with respect to the onset of nyctalopia, the onset of other visual symptoms, visual acuity, or width of visual fields. Conclusion There is no evidence to support exclusion of CHM patients from clinical trials based on their genotypes or any potential genotype–phenotype correlations.
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Affiliation(s)
- Paul R Freund
- Department of Ophthalmology and Visual Sciences University of Alberta Edmonton Alberta Canada
| | - Yuri V Sergeev
- Ophthalmic Genetics and Visual Function Branch National Eye Institute National Institutes of Health Bethesda Maryland
| | - Ian M MacDonald
- Department of Ophthalmology and Visual Sciences University of Alberta Edmonton Alberta Canada
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Shelby SJ, Feathers KL, Ganios AM, Jia L, Miller JM, Thompson DA. MERTK signaling in the retinal pigment epithelium regulates the tyrosine phosphorylation of GDP dissociation inhibitor alpha from the GDI/CHM family of RAB GTPase effectors. Exp Eye Res 2015; 140:28-40. [PMID: 26283020 DOI: 10.1016/j.exer.2015.08.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 08/10/2015] [Accepted: 08/10/2015] [Indexed: 10/25/2022]
Abstract
Photoreceptor outer segments (OS) in the vertebrate retina undergo a process of continual renewal involving shedding of disc membranes that are cleared by phagocytic uptake into the retinal pigment epithelium (RPE). In dystrophic Royal College of Surgeons (RCS) rats, OS phagocytosis is blocked by a mutation in the gene encoding the receptor tyrosine kinase MERTK. To identify proteins tyrosine-phosphorylated downstream of MERTK in the RPE, MALDI-mass spectrometry with peptide-mass fingerprinting was used in comparative studies of RCS congenic and dystrophic rats. At times corresponding to peak phagocytic activity, the RAB GTPase effector GDP dissociation inhibitor alpha (GDI1) was found to undergo tyrosine phosphorylation only in congenic rats. In cryosections of native RPE/choroid, GDI1 colocalized with MERTK and the intracellular tyrosine-kinase SRC. In cultured RPE-J cells, and in transfected heterologous cells, MERTK stimulated SRC-mediated tyrosine phosphorylation of GDI1. In OS-fed RPE-J cells, GDI1 colocalized with MERTK and SRC on apparent phagosomes located near the apical membrane. In addition, both GDI1 and RAB5, a regulator of vesicular transport, colocalized with ingested OS. Taken together, these findings identify a novel role of MERTK signaling in membrane trafficking in the RPE that is likely to subserve mechanisms of phagosome formation.
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Affiliation(s)
- Shameka J Shelby
- Department of Biological Chemistry, University of Michigan Medical School, 1150 W. Medical Center Dr., Ann Arbor, MI 48109, USA; Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, 1000 Wall St., Ann Arbor, MI 48105, USA
| | - Kecia L Feathers
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, 1000 Wall St., Ann Arbor, MI 48105, USA
| | - Anna M Ganios
- Department of Biological Chemistry, University of Michigan Medical School, 1150 W. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Lin Jia
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, 1000 Wall St., Ann Arbor, MI 48105, USA
| | - Jason M Miller
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, 1000 Wall St., Ann Arbor, MI 48105, USA
| | - Debra A Thompson
- Department of Biological Chemistry, University of Michigan Medical School, 1150 W. Medical Center Dr., Ann Arbor, MI 48109, USA; Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, 1000 Wall St., Ann Arbor, MI 48105, USA.
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A clinical molecular genetic service for United Kingdom families with choroideraemia. Eur J Med Genet 2013; 56:432-8. [DOI: 10.1016/j.ejmg.2013.06.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Accepted: 06/17/2013] [Indexed: 11/20/2022]
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Hála M, Soukupová H, Synek L, Zárský V. Arabidopsis RAB geranylgeranyl transferase beta-subunit mutant is constitutively photomorphogenic, and has shoot growth and gravitropic defects. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 62:615-27. [PMID: 20180921 DOI: 10.1111/j.1365-313x.2010.04172.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
RAB GTPases are important directional regulators of intracellular vesicle transport. Membrane localization of RAB GTPases is mediated by C-terminal double geranylgeranylation. This post-translational modification is catalyzed by the alpha-beta-heterodimer catalytic core of RAB geranylgeranyl transferase (RAB-GGT), which cooperates with the RAB escort protein (REP) that presents a nascent RAB. Here, we show that RAB-geranylgeranylation activity is significantly reduced in two homozygous mutants of the major Arabidopsis beta-subunit of RAB-GGT (AtRGTB1), resulting in unprenylated RAB GTPases accumulation in the cytoplasm. Both endocytosis and exocytosis are downregulated in rgtb1 homozygotes defective in shoot growth and morphogenesis. Root gravitropism is normal in rgtb1 roots, but is significantly compromised in shoots. Mutants are defective in etiolation and show constitutive photomorphogenic phenotypes that cannot be rescued by brassinosteroid treatment, similarly to the det3 mutant that is also defective in the secretory pathway. Transcriptomic analysis revealed an upregulation of specific RAB GTPases in etiolated wild-type plants. Taken together, these data suggest that the downregulation of the secretory pathway is interpreted as a photomorphogenic signal in Arabidopsis.
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Affiliation(s)
- Michal Hála
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojova 263, 165 02 Prague 6, Czech Republic
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Berger W, Kloeckener-Gruissem B, Neidhardt J. The molecular basis of human retinal and vitreoretinal diseases. Prog Retin Eye Res 2010; 29:335-75. [PMID: 20362068 DOI: 10.1016/j.preteyeres.2010.03.004] [Citation(s) in RCA: 392] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
During the last two to three decades, a large body of work has revealed the molecular basis of many human disorders, including retinal and vitreoretinal degenerations and dysfunctions. Although belonging to the group of orphan diseases, they affect probably more than two million people worldwide. Most excitingly, treatment of a particular form of congenital retinal degeneration is now possible. A major advantage for treatment is the unique structure and accessibility of the eye and its different components, including the vitreous and retina. Knowledge of the many different eye diseases affecting retinal structure and function (night and colour blindness, retinitis pigmentosa, cone and cone rod dystrophies, photoreceptor dysfunctions, as well as vitreoretinal traits) is critical for future therapeutic development. We have attempted to present a comprehensive picture of these disorders, including biological, clinical, genetic and molecular information. The structural organization of the review leads the reader through non-syndromic and syndromic forms of (i) rod dominated diseases, (ii) cone dominated diseases, (iii) generalized retinal degenerations and (iv) vitreoretinal disorders, caused by mutations in more than 165 genes. Clinical variability and genetic heterogeneity have an important impact on genetic testing and counselling of affected families. As phenotypes do not always correlate with the respective genotypes, it is of utmost importance that clinicians, geneticists, counsellors, diagnostic laboratories and basic researchers understand the relationships between phenotypic manifestations and specific genes, as well as mutations and pathophysiologic mechanisms. We discuss future perspectives.
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Affiliation(s)
- Wolfgang Berger
- Division of Medical Molecular Genetics and Gene Diagnostics, Institute of Medical Genetics, University of Zurich, Schorenstrasse 16, CH-8603 Schwerzenbach, Switzerland.
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Beaufrère L, Rieu S, Hache JC, Dumur V, Claustres M, Tuffery S. Altered rep-1 expression due to substitution at position +3 of the IVS13 splice-donor site of the choroideremia (CHM) gene. Curr Eye Res 2009. [DOI: 10.1080/02713689808951249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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11
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Grover S, Fishman GA. Choroidal Dystrophies. Ophthalmology 2009. [DOI: 10.1016/b978-0-323-04332-8.00085-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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Iino Y, Fujimaki T, Fujiki K, Murakami A. A novel mutation (967-970+2)delAAAGGT in the choroideremia gene found in a Japanese family and related clinical findings. Jpn J Ophthalmol 2008; 52:289-297. [PMID: 18773267 DOI: 10.1007/s10384-008-0564-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Accepted: 02/22/2008] [Indexed: 10/21/2022]
Abstract
PURPOSE To investigate the choroideremia (CHM) gene of one affected male and one obligate carrier in a Japanese family with choroideremia, and to characterize the related clinical features. METHODS We examined one affected man and one carrier woman from a Japanese family. Genomic DNA was extracted from leukocytes of peripheral blood collected from the affected man and his daughter, who is an obligate carrier of choroideremia. Exons 1-15 of the CHM gene were amplified by polymerase chain reaction (PCR) and directly sequenced. We performed ophthalmic examinations including best-corrected visual acuity, slit-lamp examination, fundus examination, electroretinography, and Goldmann perimetry. RESULTS A novel (967-970+2)delAAAGGT mutation was detected in the CHM gene. The affected man was hemizygous and had night-blindness, chorioretinal atrophy spreading from the posterior pole to the mid-periphery, and bareness of the sclera. His daughter was a heterozygous carrier who had chorioretinal atrophy and mottled appearance of the retinal pigment epithelium. CONCLUSION A novel (967-970+2)delAAAGGT mutation existed in the CHM gene of a Japanese family with choroideremia.
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Affiliation(s)
- Yutaka Iino
- Department of Ophthalmology, Juntendo University School of Medicine, Tokyo, Japan.
| | - Takuro Fujimaki
- Department of Ophthalmology, Juntendo University School of Medicine, Tokyo, Japan
| | - Keiko Fujiki
- Department of Ophthalmology, Juntendo University School of Medicine, Tokyo, Japan
| | - Akira Murakami
- Department of Ophthalmology, Juntendo University School of Medicine, Tokyo, Japan
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Olkkonen VM, Ikonen E. When intracellular logistics fails--genetic defects in membrane trafficking. J Cell Sci 2007; 119:5031-45. [PMID: 17158910 DOI: 10.1242/jcs.03303] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The number of human genetic disorders shown to be due to defects in membrane trafficking has greatly increased during the past five years. Defects have been identified in components involved in sorting of cargo into transport carriers, vesicle budding and scission, movement of vesicles along cytoskeletal tracks, as well as in vesicle tethering, docking and fusion at the target membrane. The nervous system is extremely sensitive to such disturbances of the membrane trafficking machinery, and the majority of these disorders display neurological defects--particularly diseases affecting the motility of transport carriers along cytoskeletal tracks. In several disorders, defects in a component that represents a fundamental part of the trafficking machinery fail to cause global transport defects but result in symptoms limited to specific cell types and transport events; this apparently reflects the redundancy of the transport apparatus. In groups of closely related diseases such as Hermansky-Pudlak and Griscelli syndromes, identification of the underlying gene defects has revealed groups of genes in which mutations lead to similar phenotypic consequences. New functionally linked trafficking components and regulatory mechanisms have thus been discovered. Studies of the gene defects in trafficking disorders therefore not only open avenues for new therapeutic approaches but also significantly contribute to our knowledge of the fundamental mechanisms of intracellular membrane transport.
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Affiliation(s)
- Vesa M Olkkonen
- Department of Molecular Medicine, National Public Health Institute (KTL), Biomedicum, POBox 104, FI-00251 Helsinki, Finland.
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Hildebrand MS, de Silva MG, Tan TY, Rose E, Nishimura C, Tolmachova T, Hulett JM, White SM, Silver J, Bahlo M, Smith RJ, Dahl HHM. Molecular characterization of a novel X-linked syndrome involving developmental delay and deafness. Am J Med Genet A 2007; 143A:2564-75. [DOI: 10.1002/ajmg.a.31995] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Protein Prenylation: An (Almost) Comprehensive Overview on Discovery History, Enzymology, and Significance in Physiology and Disease. MONATSHEFTE FUR CHEMIE 2006. [DOI: 10.1007/s00706-006-0534-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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16
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Futter CE. The molecular regulation of organelle transport in mammalian retinal pigment epithelial cells. ACTA ACUST UNITED AC 2006; 19:104-11. [PMID: 16524426 DOI: 10.1111/j.1600-0749.2006.00303.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Retinal pigment epithelial cells contain large numbers of melanosomes that can enter the apical processes extending between the outer segments of the overlying photoreceptors. Every day the distal portion of the photoreceptor outer segment is shed and phagocytosed by the retinal pigment epithelial cell. The phagosome is then transported into the cell body and the contents degraded by lysosomal enzymes. This review focuses on recent progress made in the identification of molecules that regulate the transport of melanosomes into the apical processes and the transport of phagosomes into the cell body. Myosin VIIa is a key player in both processes and, at least in the case of melanosome movement, myosin VIIa is recruited to the melanosome via the GTPase, Rab27a. The possible role played by defects in the transport of melanosomes and phagosomes in the development of retinal degenerative diseases is discussed.
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Affiliation(s)
- Clare E Futter
- Division of Cell Biology, Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK.
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Itabashi T, Wada Y, Kawamura M, Sato H, Tamai M. Clinical features of Japanese families with a 402delT or a 555-556delAG mutation in choroideremia gene. Retina 2005; 24:940-5. [PMID: 15579993 DOI: 10.1097/00006982-200412000-00015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To characterize the clinical features of two Japanese families with choroideremia associated with a 402delT and a 555-556delAG mutation in the choroideremia gene (CHM). METHODS Four affected members and one obligate carrier from two Japanese families with choroideremia were studied. To detect mutations of the CHM gene, the products of polymerase chain reaction were directly sequenced in both directions. The ophthalmologic examination included best-corrected visual acuity, slit-lamp examination, fundus examination, kinetic perimetry, electroretinography, and fluorescein angiography. RESULTS A 402delT and a 555-556delAG mutation were found in two Japanese families with choroideremia. All affected members had night-blindness, progressive constriction of the visual field, chorioretinal atrophy, and mottled appearance of the retinal pigment epithelium. The obligate carrier had mild patchy areas of retinal pigment epithelial atrophy with no visual symptoms. CONCLUSION The authors found a 402delT and a 555-556delAG mutation in the CHM gene, one of which (402delT) is a novel mutation. They conclude that these mutations cause choroideremia in Japanese families.
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Affiliation(s)
- Toshitaka Itabashi
- Department of Ophthalmology, Tohoku University School of Medicine, Sendai, Japan.
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García-Hoyos M, Sanz R, Diego-Alvarez D, Lorda-Sánchez I, Trujillo-Tiebas MJ, Cantalapiedra D, Ramos C, Ayuso C. New approach for the refinement of the location of the X-chromosome breakpoint in a previously described female patient with choroideremia carrying a X;4 translocation. Am J Med Genet A 2005; 138:365-8. [PMID: 16222660 DOI: 10.1002/ajmg.a.30987] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Choroideremia (CHM) is an X-linked recessive ophthalmic disease characterized by a progressive degeneration of the choroid and the pigmented epithelium of the retina. We present the genetic characterization of a female patient affected with CHM who has been previously studied cytogenetically and showed a balanced translocation between chromosomes X and 4 [46,X,t(X;4)(q21;p16)]. The breakpoint in the X chromosome lies in the locus of CHM gene and for this reason, we have elucidated whether or not CHM was disrupted in the X chromosome involved in the translocation using different techniques. FISH showed that the 3'UTR and the last exons of the CHM were on the der(X) chromosome, and the 5'UTR and first exons of this gene were on the der(4) chromosome. Expression level analysis revealed that the breakpoint in the der(X) was located between exons 8 and 9 of the CHM gene because the expression level decreased from this point onwards. Based on this result the expression level analysis proved to be a valid method to pinpoint the location of breakpoints when the gene being expressed in peripheral blood is disrupted. Our results confirmed that the CHM gene was indeed disrupted in the X chromosome involved in the translocation. Besides, the nonrandom inactivation of the normal X chromosome observed using a methylation-specific polymerase chain reaction (M-PCR) technique explained the CHM in the female patient.
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Affiliation(s)
- M García-Hoyos
- Departamento de Genética, Fundación Jiménez Díaz. Avda. Reyes Católicos 2, Madrid, España
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19
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Potter MJ, Wong E, Szabo SM, McTaggart KE. Clinical findings in a carrier of a new mutation in the choroideremia gene. Ophthalmology 2004; 111:1905-9. [PMID: 15465555 DOI: 10.1016/j.ophtha.2004.04.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2003] [Accepted: 04/21/2004] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVE To describe the clinical and molecular findings of a female carrier of a new mutation in the choroideremia (CHM) gene. DESIGN Single interventional case report. METHODS A 27-year-old woman was seen with mild difficulties with dark adaptation and a history of a retinal degeneration in her father and choroideremia in 3 male paternal first cousins. Visual acuity measurements, peripheral and color vision tests, electroretinography (ERG), Goldmann visual fields, fluorescein angiogram, computed tomography scan, and DNA analysis were performed. MAIN OUTCOME MEASURES (1) Visual fields, (2) fluorescein angiography, and (3) DNA analysis. RESULTS Visual acuity decreased from 20/30 to 10/200 in the right eye abruptly over 2 months, then remained stable over 2 years of follow-up and remained 20/25 in the left eye. Goldmann visual fields showed development of a central scotoma in the right eye concurrent with the rapid decline. A small amount of subretinal hemorrhage was visible on dilated fundus examination at that time, but definite leakage was not evident on fluorescein angiography; afterwards, a choroidal neovascular membrane (CNV) was suspected. The ERG was normal. DNA analysis revealed that the patient was heterozygous for a previously undescribed substitution mutation at the 3'-splice site of intron 6 of the CHM gene (850-1 G to C), confirmed by mRNA analysis with reverse transcriptase polymerase chain reaction. CONCLUSIONS Severe visual acuity loss rarely occurs in female carriers of choroideremia mutations. The diagnosis should be considered in patients with a suitable family history and fundus findings. Physicians should consider the possibility of CNV development in such patients, which may be a response to abnormal retinal pigment epithelium. Recognition of this new mutation may help identify patients who could benefit from current and future treatments to protect against vision loss.
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Affiliation(s)
- Michael J Potter
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, Canada
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20
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Shi W, van den Hurk JAJM, Alamo-Bethencourt V, Mayer W, Winkens HJ, Ropers HH, Cremers FPM, Fundele R. Choroideremia gene product affects trophoblast development and vascularization in mouse extra-embryonic tissues. Dev Biol 2004; 272:53-65. [PMID: 15242790 DOI: 10.1016/j.ydbio.2004.04.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2003] [Revised: 04/09/2004] [Accepted: 04/09/2004] [Indexed: 11/27/2022]
Abstract
Choroideremia (CHM) is a hereditary eye disease caused by mutations in the X-linked CHM gene. Disruption of the Chm gene in mice resulted in prenatal death of Chm-/Y males and Chm-/Chm+ females that had inherited the mutation from their mothers. Male chimeras and Chm+/Chm- females with paternal transmission of the mutation were viable and had photoreceptor degeneration reminiscent of human choroideremia. Here, we show that Chm-/Y males and Chm-/Chm+ females were retarded at e7.5 and died before e11.5 due to multiple defects of the extra-embryonic tissues. Mutant embryos exhibited deficiency of diploid trophoblasts associated with overabundance of giant cells. In yolk sac and placenta, severe defects in vasculogenesis were obvious. Chm-/Y males exhibited more pronounced phenotypes than Chm-/Chm+ females. The lethal genotypes could be rescued by tetraploid aggregation. Chm-/Chm+ females, but not Chm-/Y males, could also be rescued when their Chm+/Chm- mothers were mated with Mus spretus males. Backcross analysis suggested that the viability of interspecies hybrid Chm-/Chm+ females may be due to expression from the Chm allele on the M. spretus X-chromosome rather than a modifier effect. Our results demonstrate that Chm is essential for diploid trophoblast development and plays a role in the vascularization in placenta and yolk sac.
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Affiliation(s)
- Wei Shi
- Max-Planck-Institute for Molecular Genetics, Berlin-Dahlem, Germany
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21
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van den Hurk JAJM, van de Pol DJR, Wissinger B, van Driel MA, Hoefsloot LH, de Wijs IJ, van den Born LI, Heckenlively JR, Brunner HG, Zrenner E, Ropers HH, Cremers FPM. Novel types of mutation in the choroideremia ( CHM) gene: a full-length L1 insertion and an intronic mutation activating a cryptic exon. Hum Genet 2003; 113:268-75. [PMID: 12827496 DOI: 10.1007/s00439-003-0970-0] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2003] [Accepted: 05/07/2003] [Indexed: 10/26/2022]
Abstract
Choroideremia (CHM) is a progressive chorioretinal degeneration caused by mutations in the widely expressed CHM gene on chromosome Xq21. The product of this gene, Rab escort protein (REP)-1, is involved in the posttranslational lipid modification and subsequent membrane targeting of Rab proteins, small GTPases that play a key role in intracellular trafficking. We have searched for mutations of the CHM gene in patients with choroideremia by analysis of individual CHM exons and adjacent intronic sequences PCR-amplified from genomic DNA and by reverse transcription (RT)-PCR analysis of the coding region of the CHM mRNA. In 35 patients, at least 21 different causative CHM defects were identified. These included two partial CHM gene deletions and an insertion of a full-length L1 retrotransposon into the coding region of the CHM gene, a type of mutation that has not been previously reported as a cause of CHM. We also detected nine different nonsense mutations, five of which are recurrent, a small deletion, a small insertion, and at least five distinct splice site mutations, one of which has been described previously. Moreover, we report for the first time the identification of an intronic mutation remote from the exon-intron junctions that creates a strong acceptor splice site and leads to the inclusion of a cryptic exon into the CHM mRNA. Finally, in an affected male who did not have a mutation in any of the CHM exons or their splice sites, the deletion of a complete exon from the CHM mRNA was observed.
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Affiliation(s)
- José A J M van den Hurk
- Department of Human Genetics, University Medical Center Nijmegen, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.
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22
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Duncan JL, Aleman TS, Gardner LM, De Castro E, Marks DA, Emmons JM, Bieber ML, Steinberg JD, Bennett J, Stone EM, MacDonald IM, Cideciyan AV, Maguire MG, Jacobson SG. Macular pigment and lutein supplementation in choroideremia. Exp Eye Res 2002; 74:371-81. [PMID: 12014918 DOI: 10.1006/exer.2001.1126] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Choroideremia is an incurable X-linked retinal degeneration caused by mutations in the gene encoding Rab escort protein-1. A group of clinically defined and genotyped patients were studied to determine: (1) the degree of rod and cone dysfunction and structural abnormality in the central retina and the level of macular pigment; and (2) the response of macular pigment and foveal vision to a 6 month trial of supplementation with oral lutein (at 20 mg per day). Rod and cone-mediated function was measured with dark-adapted static perimetry; in vivo retinal structure was determined with optical coherence tomography; and macular pigment optical density was measured with heterochromatic flicker photometry. In this cohort of patients (ages 15-65 years), both rod- and cone-mediated central function declined with age as did central retinal thickness. Macular pigment levels did not differ between patients and male control subjects. Supplementation of oral lutein in a subset of patients led to an increase in serum lutein and macular pigment levels; absolute foveal sensitivity did not change. It is concluded that macular pigment density can be augmented by oral intake of lutein in patients with choroideremia. There was no short-term change in the central vision of the patients on the supplement, but long-term influences of lutein supplementation on disease natural history warrant further study.
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Affiliation(s)
- Jacque L Duncan
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
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Abstract
Choroideremia is an X-chromosome-linked disease that leads to the degeneration of the choriocapillaris, the retinal pigment epithelium and the photoreceptor layer in the eye. The gene product defective in choroideremia, CHM, is identical to Rab escort protein 1 (REP1). CHM/REP1 is an essential component of the catalytic geranylgeranyltransferase II complex (GGTrII) that delivers newly synthesized small GTPases belonging to the RAB gene family to the catalytic complex for post-translational modification. CHM/REP family members are evolutionarily related to members of the guanine nucleotide dissociation inhibitor (GDI) family, proteins involved in the recycling of Rab proteins required for vesicular membrane trafficking through the exocytic and endocytic pathways, forming the GDI/CHM superfamily. Biochemical and structural analyses have now revealed a striking parallel in the organization and function of these two families allowing us to generate a general model for GDI/CHM superfamily function in health and disease.
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Affiliation(s)
- C Alory
- Departments of Cell and Molecular Biology and Institute for Childhood and Neglected Diseases, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
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24
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Affiliation(s)
- V M Olkkonen
- Department of Biochemistry, National Public Health Institute, Helsinki, Finland
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25
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van den Hurk JA, Schwartz M, van Bokhoven H, van de Pol TJ, Bogerd L, Pinckers AJ, Bleeker-Wagemakers EM, Pawlowitzki IH, Rüther K, Ropers HH, Cremers FP. Molecular basis of choroideremia (CHM): mutations involving the Rab escort protein-1 (REP-1) gene. Hum Mutat 2000; 9:110-7. [PMID: 9067750 DOI: 10.1002/(sici)1098-1004(1997)9:2<110::aid-humu2>3.0.co;2-d] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Choroideremia (CHM) is an X-linked recessive eye disease that results from mutations involving the Rab escort protein-1 (REP-1) gene. In 18 patients deletions of different sizes have been found. Two females suffering from CHM were reported to have translocations that disrupt the REP-1 gene. In 22 patients, small mutations have been identified. Interestingly, these are all nonsense, frameshift or splice-site mutations; with one possible exception, missense mutations have not been found. This comprises all the known mutations in the disease.
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Affiliation(s)
- J A van den Hurk
- Department of Human Genetics, University Hospital Nijmegen, The Netherlands
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26
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Yarovinsky TO, Rickman DW, Diamond RH, Taub R, Hageman GS, Bowes Rickman C. Expression of the protein tyrosine phosphatase, phosphatase of regenerating liver 1, in the outer segments of primate cone photoreceptors. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2000; 77:95-103. [PMID: 10814835 DOI: 10.1016/s0169-328x(00)00045-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Foveal cone photoreceptors are morphologically distinct and, presumably, express unique transcripts. We have identified a cDNA clone encoding the protein tyrosine phosphatase (PTP), phosphatase of regenerating liver 1 (PRL-1) in a screen for genes that are enriched in monkey fovea. PRL-1 was originally isolated as an immediate early gene in regenerating liver [R.H. Diamond, D.E. Cressman, T.M. Laz, C.S. Abrams, R. Taub, PRL-1, a unique nuclear protein tyrosine phosphatase, affects cell growth, Mol. Cell Biol. 14 (1994) 3752-3762]. On cDNA Southern blots of human and monkey retina, radiolabeled PRL-1 cDNA hybridized to a single mRNA species of about 2.5 kb that was most intense in fovea-enriched samples. The monkey PRL-1 deduced amino acid sequence is identical to human, rat and mouse PRL-1. Affinity-purified antibodies directed against PRL-1 preferentially labeled cone photoreceptor cells and a subpopulation of bipolar cells in monkey retina. Immunoreactivity in cones was confined to red and green, but not to blue, cones and was restricted to the outer segments. Immunolocalization also revealed that PRL-1 protein expression was non-nuclear, suggesting that its function in the retina may be unrelated to its role in other tissues where it is expressed primarily in nuclei. Although both foveal and extrafoveal cones were PRL-1 reactive, the high abundance of PRL-1 mRNAs detected in monkey fovea correlates with the high concentration of cones in the fovea. The PRL-1 gene is located on chromosome 6q within an interval that also contains the genes that cause two hereditary retinal dystrophies. These studies demonstrate novel expression of the PRL-1 gene in the neural retina and suggest the phosphatase activity of PRL-1 may modulate normal cone photoreceptor cell function.
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Affiliation(s)
- T O Yarovinsky
- Department of Ophthalmology and Visual Sciences, University of Iowa College of Medicine, 200 Hawkins Blvd., Iowa City, IA, USA
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27
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Beaufrère L, Tuffery S, Hamel C, Bareil C, Arnaud B, Demaille J, Claustres M. The protein truncation test (PTT) as a method of detection for choroideremia mutations. Exp Eye Res 1997; 65:849-54. [PMID: 9441709 DOI: 10.1006/exer.1997.0392] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The predominance of truncative mutations responsible for choroideremia (CHM) led us to investigate the use of the protein truncation test (PTT) applied to lymphocyte RNA derived from affected males as a scanning method. The entire CHM coding region was reversed-transcribed in three overlapping cDNA segments (RT-PCR) which were amplified and further analysed by PTT after in vitro transcription/ translation. This strategy enabled us to detect the CHM-causative alteration in each of the four unrelated patients from southern France who were investigated. We describe three novel mutations (E177X, 323delT, 1313delTC), and report one recurrent mutation (R267X) in CHM. We believe this to be the first attempt at applying RT-PCR-PTT to CHM mutation detection.
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Affiliation(s)
- L Beaufrère
- Laboratoire de Biochimie Génétique, CNRS ERS 155, Institut de Biologie, Montpellier, France
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28
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Farber DB, Danciger M. Identification of genes causing photoreceptor degenerations leading to blindness. Curr Opin Neurobiol 1997; 7:666-73. [PMID: 9384551 DOI: 10.1016/s0959-4388(97)80087-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
At least 15 genes with defects responsible for various forms of inherited retinal disease involving photoreceptor loss have been identified over the past eight years. Several of the genes were first considered as candidates for study because of their involvement in murine retinal disease, others because of their chromosomal loci. In two cases, novel genes were uncovered by positional cloning. Based on reports of disease loci for which no gene has yet been found, more than twice as many genes remain to be identified in this genetically heterogeneous group of diseases.
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Affiliation(s)
- D B Farber
- Jules Stein Eye Institute, University of California at Los Angeles, School of Medicine, Los Angeles, California 90024-7008, USA.
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29
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van den Hurk JA, Hendriks W, van de Pol DJ, Oerlemans F, Jaissle G, Rüther K, Kohler K, Hartmann J, Zrenner E, van Bokhoven H, Wieringa B, Ropers HH, Cremers FP. Mouse choroideremia gene mutation causes photoreceptor cell degeneration and is not transmitted through the female germline. Hum Mol Genet 1997; 6:851-8. [PMID: 9175730 DOI: 10.1093/hmg/6.6.851] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Choroideremia (CHM) is an X-linked progressive eye disorder which results from defects in the human Rab escort protein-1 (REP-1) gene. A gene targeting approach was used to disrupt the mouse chm/rep-1 gene. Chimeric males transmitted the mutated gene to their carrier daughters but, surprisingly, these heterozygous females had neither affected male nor carrier female offspring. The targeted rep-1 allele was detectable, however, in male as well as female blastocyst stage embryos isolated from a heterozygous mother. Thus, disruption of the rep-1 gene gives rise to lethality in male embryos; in female embryos it is only lethal if the mutation is of maternal origin. This observation can be explained by preferential inactivation of the paternal X chromosome in murine extraembryonic membranes suggesting that expression of the rep-1 gene is essential in these tissues. In both heterozygous females and chimeras the rep-1 mutation causes photoreceptor cell degeneration. Consequently, conditional rescue of the embryonic lethal phenotype of the rep-1 mutation may provide a faithful mouse model for choroideremia.
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Affiliation(s)
- J A van den Hurk
- Department of Human Genetics, University Hospital Nijmegen, The Netherlands.
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31
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van den Hurk JA, Schwartz M, van Bokhoven H, van de Pol TJ, Bogerd L, Pinckers AJ, Bleeker-Wagemakers EM, Pawlowitzki IH, Rüther K, Ropers HH, Cremers FP. Molecular basis of choroideremia (CHM): mutations involving the Rab escort protein-1 (REP-1) gene. Hum Mutat 1997. [PMID: 9067750 DOI: 10.1002/(sici)1098-1004(1997)9:2%3c110::aid-humu2%3e3.0.co;2-d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Choroideremia (CHM) is an X-linked recessive eye disease that results from mutations involving the Rab escort protein-1 (REP-1) gene. In 18 patients deletions of different sizes have been found. Two females suffering from CHM were reported to have translocations that disrupt the REP-1 gene. In 22 patients, small mutations have been identified. Interestingly, these are all nonsense, frameshift or splice-site mutations; with one possible exception, missense mutations have not been found. This comprises all the known mutations in the disease.
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Affiliation(s)
- J A van den Hurk
- Department of Human Genetics, University Hospital Nijmegen, The Netherlands
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32
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Bauer BE, Lorenzetti S, Miaczynska M, Bui DM, Schweyen RJ, Ragnini A. Amino- and carboxy-terminal domains of the yeast Rab escort protein are both required for binding of Ypt small G proteins. Mol Biol Cell 1996; 7:1521-33. [PMID: 8898359 PMCID: PMC276003 DOI: 10.1091/mbc.7.10.1521] [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: 02/02/2023] Open
Abstract
The Rab escort protein (REP) is an essential component of the heterotrimeric enzyme Rab geranylgeranyl transferase that modifies the carboxy-terminal cysteines of the Ras-like small G proteins belonging to the Rab/Ypt family. Deletions in the human CHM locus, encoding one of the two REPs known in humans, result in a retinal degenerative syndrome called choroideremia. The only known yeast homologue of the choroideremia gene product is encoded by an essential gene called MRS6. Besides three structurally conserved regions (SCRs) previously detected in the amino-terminal half of REPs and RabGDIs, three other regions in the carboxy-terminal domain (RCR 1-3) are here identified as being characteristic of REPs alone. We have performed the first mutational analysis of a REP protein to experimentally define the regions functionally important for Rab/Ypt protein binding, making use of the genetic system of the yeast Saccharomyces cerevisiae. This analysis has shown that the SCRs are necessary but not sufficient for Ypt1p binding by the yeast REP, the carboxy-terminal region also being required.
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Affiliation(s)
- B E Bauer
- Vienna Biocenter, University of Vienna, Austria
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33
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Van Bokhoven H, Van den Hurk JA, Bogerd L, Van de Pol DJ, Ropers HH, Cremers FP. A highly polymorphic microsatellite marker located within the choroideremia gene. Ophthalmic Genet 1996; 17:119-21. [PMID: 8905853 DOI: 10.3109/13816819609057115] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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35
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Abstract
Choroideremia, an X-linked form of retinal degeneration, results from defects in the Rab escort protein-1 (REP-1) gene. REP-1 and REP-2 assist in the attachment of geranylgeranyl groups to Rab GTPases, a modification essential for their action as molecular switches regulating intracellular vesicular transport. If Rabs that depend preferentially on REP-1 for prenylation exist, they will accumulate unprenylated in choroideremia cells. Using recombinant Rab geranylgeranyl transferase and REPs to label unprenylated cytosolic proteins, we identified one unprenylated protein in choroideremia lymphoblasts that was prenylated in vitro more efficiently by REP-1 than by REP-2. This protein was purified and identified as Ram (renamed Rab27), a previously cloned Rab of unknown function. Immunohistochemistry of rat retina showed that Ram/Rab27 is expressed in the pigment epithelium and choriocapillaris, the two retinal cell layers that degenerate earliest in choroideremia. These results raise the possibility that the retinal degeneration in choroideremia results from the deficient geranylgeranylation of Ram/Rab27 or a closely related protein.
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Affiliation(s)
- M C Seabra
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235, USA
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36
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Abstract
PURPOSE To assess the state of knowledge of photoreceptor dystrophies. METHODS The current literature concerning photoreceptor dystrophies is reviewed, and their potential impact on concepts of pathogenesis of disease and clinical practice is assessed. RESULTS As a result of cooperative investigative work between researchers in various disciplines, major advances in the classification of retinal photoreceptor dystrophies have been made. Until recently, classification of retinal dystrophies was based on clinical observation alone, and it was evident that this method was imprecise and of limited value. Largely through the work of molecular biologists, it has been shown that diseases clinically indistinguishable from one another may be a result of mutations on a variety of genes; conversely, different mutations on a single gene may give rise to a variety of phenotypes. It is reassuring that it is possible to generate concepts as to potential pathogenetic mechanisms that exist in retinal dystrophies in light of this new knowledge. More important for the clinician is the potential impact on clinical practice. There is as yet no therapy by which the course of most of these disorders can be modified. However, there is a considerable body of work in which therapeutic intervention is being explored, and many researchers now see treatment as a justifiable objective of their work. CONCLUSIONS Knowledge of the causative mutation is of value to the clinician in that it provides a precise diagnosis and allows the distribution of the abnormal gene to be documented fully within a family. To take full advantage of the opportunities provided by current research, clinical practice will have to be modified, particularly if therapy can be justified.
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Affiliation(s)
- A C Bird
- Institute of Ophthalmology, Moorfields Eye Hospital, London University, United Kingdom
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37
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Rosenberg T, Schwartz M. Age differences of visual field impairment and mutation spectrum in Danish choroideremia patients. Acta Ophthalmol 1994; 72:678-82. [PMID: 7747574 DOI: 10.1111/j.1755-3768.1994.tb04679.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Visual prognosis is a crucial theme in the counselling of individuals affected by a progressive retinal dystrophy. Unfortunately prognostic predictions are hampered by large interindividual differences in disease courses even within well defined nosological entities. Ten patients from 8 families affected by choroideremia were studied. The clinical signs in our patients were rather uniform. Deterioration of the peripheral visual fields typically began in the second decade of life, and progressed during the following one or two decades. Esterman transformation of peripheral visual field measurements was chosen as the best single indicator of visual impairment. Noticeable age differences in residual visual fields among patients were demonstrated. The age difference between the mildest and the severest cases amounted to 25 years. One of the expectations of the exploration of disease genes, is the potential predictive value of mutation identification with regard to phenotypic variability. Different presumed causative mutations were identified. Nevertheless, all the mutations are predicted to cause premature stops during translation, resulting in a non-functional or missing protein. Consequently, the observed age variation in the photopic visual field degradation must be due to still unrecognized factors, either constitutional and/or environmental.
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Affiliation(s)
- T Rosenberg
- National Eye Clinic for the Visually Impaired, Copenhagen, Denmark
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Rosenfeld PJ, McKusick VA, Amberger JS, Dryja TP. Recent advances in the gene map of inherited eye disorders: primary hereditary diseases of the retina, choroid, and vitreous. J Med Genet 1994; 31:903-15. [PMID: 7891370 PMCID: PMC1016688 DOI: 10.1136/jmg.31.12.903] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- P J Rosenfeld
- Howe Laboratory, Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston 02114
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Sedlacek Z, Konecki DS, Korn B, Klauck SM, Poustka A. Evolutionary conservation and genomic organization of XAP-4, an Xq28 located gene coding for a human rab GDP-dissociation inhibitor (GDI). Mamm Genome 1994; 5:633-9. [PMID: 7849400 DOI: 10.1007/bf00411459] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
After the development of efficient methods for the construction of transcription maps of defined genomic regions, the rate-limiting step in the analysis of the coding potentials of these regions is the elucidation of function of the novel genes and the examination of their possible involvement in hereditary diseases localized to the region. This can be greatly facilitated by the detection of sequence homology to a gene of known function. XAP-4 is one of the genes identified in the G6PD region of the human Xq28 by direct cDNA selection. The rapid assembly of this gene and the determination of its function was possible because of its sequence homology with the bovine smg p25A/rab3A GDP dissociation inhibitor (GDI). Sequence comparison with other GDIs in the databases has revealed that XAP-4 belongs to one of at least two distinct classes of mammalian rab GDIs. The rab GDIs, which play an important role in the regulation of cellular transport, are highly evolutionarily conserved, as are several other genes identified in the neighborhood of XAP-4. This genomic region is very gene dense, and all the cDNA clones from the approximately 2.5-kb-long transcript of XAP-4 map to a single 7.5-kb genomic EcoRI fragment. The genomic organization of XAP-4 has been examined to determine the distribution of the exonic sequences within this short segment of genomic DNA. It was found that, similar to several other genes from the region, XAP-4 is split into exons of average size, which are interrupted by very short introns.
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Affiliation(s)
- Z Sedlacek
- Deutsches Krebsforschungszentrum, Heidelberg, Germany
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Powell CM, Taggart RT, Drumheller TC, Wangsa D, Qian C, Nelson LM, White BJ. Molecular and cytogenetic studies of an X;autosome translocation in a patient with premature ovarian failure and review of the literature. AMERICAN JOURNAL OF MEDICAL GENETICS 1994; 52:19-26. [PMID: 7977456 DOI: 10.1002/ajmg.1320520105] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We have identified a patient with premature ovarian failure (POF) and a balanced X;autosome translocation: 46,X,t(X;6)(q13.3 or q21;p12) using high-resolution cytogenetic analysis and FISH. BrdU analysis showed that her normal X was late-replicating and translocated X earlier-replicating which is typical of balanced X;autosome rearrangements. Molecular studies were done to characterize the breakpoint on Xq and to determine the parental origin. PCR probes of tetranucleotide and dinucleotide repeat polymorphisms, and genomic probes were used to study DNA from the patient, her chromosomally normal parents and brother, and somatic cell hybrids containing each translocation chromosome. The translocation is paternally derived and is localized to Xq13.3-proximal Xq21.1, between PGK1 and DXS447 loci, a distance of 0.1 centimorgans. A "critical region" for normal ovarian function has been proposed for Xq13-q26 [Sarto et al., Am J Hum Genet 25:262-270, 1973; Phelan et al., Am J Obstet Gynecol 129:607-613, 1977; Summitt et al., BD:OAS XIV(6C):219-247, 1978] based on cytogenetic and clinical studies of patients with X;autosome translocations. Few cases have had molecular characterization of the breakpoints to further define the region. While translocations in the region may lead to ovarian dysfunction by disrupting normal meiosis or by a position effect, two recent reports of patients with premature ovarian failure and Xq deletions suggest that there is a gene (POF1) localized to Xq21.3-q27 [Krauss et al., N Engl J Med 317:125-131, 1987; Davies et al., Cytogenet Cell Genet 58:853-966, 1991] or within Xq26.1-q27 [Tharapel et al., Am J Hum Genet 52:463-471, 1993] responsible for POF.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- C M Powell
- Interinstitute Medical Genetics Program, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
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Fujimura K, Tanaka K, Nakano A, Toh-e A. The Saccharomyces cerevisiae MSI4 gene encodes the yeast counterpart of component A of Rab geranylgeranyltransferase. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37095-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Tommerup N. Mendelian cytogenetics. Chromosome rearrangements associated with mendelian disorders. J Med Genet 1993; 30:713-27. [PMID: 8411066 PMCID: PMC1016528 DOI: 10.1136/jmg.30.9.713] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- N Tommerup
- Danish Centre for Human Genome Research, John F Kennedy Institute, Glostrup, Denmark
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Waldherr M, Ragnini A, Schweyer RJ, Boguski MS. MRS6--yeast homologue of the choroideraemia gene. Nat Genet 1993; 3:193-4. [PMID: 8387377 DOI: 10.1038/ng0393-193] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Seabra MC, Brown MS, Goldstein JL. Retinal degeneration in choroideremia: deficiency of rab geranylgeranyl transferase. Science 1993; 259:377-81. [PMID: 8380507 DOI: 10.1126/science.8380507] [Citation(s) in RCA: 318] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Rab geranylgeranyl transferase (GG transferase) is a two-component enzyme that attaches 20-carbon isoprenoid groups to cysteine residues in Rab proteins, a family of guanosine triphosphate-binding proteins that regulate vesicular traffic. The mutant gene in human choroideremia, an X-linked form of retinal degeneration, encodes a protein that resembles component A of rat Rab GG transferase. Lymphoblasts from choroideremia subjects showed a marked deficiency in the activity of component A, but not component B, of Rab GG transferase. The deficiency was more pronounced when the substrate was Rab3A, a synaptic vesicle protein, than it was when the substrate was Rab1A, a protein of the endoplasmic reticulum. The data imply the existence of multiple component A proteins, one of which is missing in choroideremia.
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Affiliation(s)
- M C Seabra
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235
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