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Hereditary Diseases of the Retina. Neuroophthalmology 2016. [DOI: 10.1007/978-3-319-28956-4_36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Audo I, Robson AG, Holder GE, Moore AT. The negative ERG: clinical phenotypes and disease mechanisms of inner retinal dysfunction. Surv Ophthalmol 2008; 53:16-40. [PMID: 18191655 DOI: 10.1016/j.survophthal.2007.10.010] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Inner retinal dysfunction is encountered in a number of retinal disorders, either inherited or acquired, as a primary or predominant defect. Fundus examination is rarely diagnostic in these disorders, although some show characteristic features, and careful electrophysiological assessment of retinal function is needed for accurate diagnosis. The ERG in inner retinal dysfunction typically shows a negative waveform with a preserved a-wave and a selectively reduced b-wave. Advances in retinal physiology and molecular genetics have led to a greater understanding of the pathogenesis of these disorders. This review summarizes current knowledge on normal retinal physiology, the investigative techniques used and the range of clinical disorders in which there is predominantly inner retinal dysfunction.
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Nunnery C, Pickett JP, Zimmerman KL. Congenital stationary night blindness in a Thoroughbred and a Paso Fino. Vet Ophthalmol 2006; 8:415-9. [PMID: 16359365 DOI: 10.1111/j.1463-5224.2005.00416.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This report documents congenital stationary night blindness (CSNB) in two non-Appaloosa horse breeds (Thoroughbred and Paso Fino). History of vision impairment since birth, normal ocular structures on ophthalmic examination, and electroretinographic findings were consistent with CSNB. In one horse (Thoroughbred), a 9-year follow-up was carried out. In the Paso Fino, severe vision impairment from birth to approximately 1 year of age in both dim and bright light situations led to humane euthanasia and histopathologic confirmation of the disorder.
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Affiliation(s)
- Catherine Nunnery
- Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0442, USA
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Jalkanen R, Mäntyjärvi M, Tobias R, Isosomppi J, Sankila EM, Alitalo T, Bech-Hansen NT. X linked cone-rod dystrophy, CORDX3, is caused by a mutation in the CACNA1F gene. J Med Genet 2006; 43:699-704. [PMID: 16505158 PMCID: PMC2564595 DOI: 10.1136/jmg.2006.040741] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND X linked cone-rod dystrophy (CORDX) is a recessive retinal disease characterised by progressive dysfunction of photoreceptors. It is genetically heterogeneous, showing linkage to three X chromosomal loci. CORDX1 is caused by mutations in the RPGR gene (Xp21.1), CORDX2 is located on Xq27.2-28, and we recently localised CORDX3 to Xp11.4-q13.1. We aimed to identify the causative gene behind the CORDX3 phenotype. METHODS All 48 exons of the CACNA1F gene were screened for mutations by DNA sequencing. RNA from cultured lymphoblasts and peripheral blood activated T lymphocytes was analysed by RT-PCR and sequencing. RESULTS A novel CACNA1F mutation, IVS28-1 GCGTC>TGG, in the splice acceptor site of intron 28 was identified. Messenger RNA studies indicated that the identified mutation leads to altered splicing of the CACNA1F transcript. Aberrant splice variants are predicted to result in premature termination and deletions of the encoded protein, Ca(v)1.4 alpha1 subunit. CONCLUSION CACNA1F mutations cause the retinal disorder, incomplete congenital stationary night blindness (CSNB2), although mutations have also been detected in patients with divergent diagnoses. Our results indicate that yet another phenotype, CORDX3, is caused by a mutation in CACNA1F. Clinically, CORDX3 shares some features with CSNB2 but is distinguishable from CSNB2 in that it is progressive, can begin in adulthood, has no nystagmus or hyperopic refraction, has only low grade astigmatism, and in dark adaptation lacks cone threshold and has small or no elevation of rod threshold. Considering all features, CORDX3 is more similar to other X chromosomal cone-rod dystrophies than to CSNB2.
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Weleber RG, Gregory-Evans K. Retinitis Pigmentosa and Allied Disorders. Retina 2006. [DOI: 10.1016/b978-0-323-02598-0.50023-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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Michaelides M, Johnson S, Bradshaw K, Holder GE, Simunovic MP, Mollon JD, Moore AT, Hunt DM. X-Linked Cone Dysfunction Syndrome with Myopia and Protanopia. Ophthalmology 2005; 112:1448-54. [PMID: 15953640 DOI: 10.1016/j.ophtha.2005.02.021] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2004] [Accepted: 02/21/2005] [Indexed: 11/30/2022] Open
Abstract
PURPOSE To perform a detailed clinical, psychophysical, and molecular assessment of members of 4 families with an unusual X-linked cone dysfunction syndrome associated with myopia. PARTICIPANTS Affected and unaffected members of 4 British nonconsanguineous families. METHODS Subjects underwent both detailed clinical examination and psychophysical testing. After informed consent was obtained, blood samples were taken for DNA extraction, and molecular genetic analysis was performed. The strategy for molecular analysis was to amplify the coding regions of the long and middle wavelength-sensitive cone opsin genes and the upstream locus control region by polymerase chain reaction and to examine these fragments for mutations by sequencing of DNA. RESULTS The phenotype was almost identical in all 4 families, consisting of moderate to high myopia, astigmatism, moderately reduced acuity, and normal fundi. Electroretinography showed abnormal cone but normal rod responses. Psychophysical testing showed a selective impairment of long cones in combination with well-preserved middle cone and short cone function. There was no evidence to suggest that the phenotype was progressive. Molecular analysis of the X-linked opsin gene array in the 4 families indicated that affected males have inherited the same X-chromosome from their mother. In 2 families, a long/middle hybrid gene was detected. In a third family, the commonly described deleterious Cys203Arg amino acid substitution was identified in both the long and middle opsin genes. In the fourth family, the only abnormality was absence of a middle opsin exon 2; the cause of the protanopia in this family is uncertain. CONCLUSIONS The X-linked cone dysfunction syndrome associated with myopia and dichromacy described here has many similarities to Bornholm eye disease, a condition previously mapped to Xq28. Except for the Cys203Arg substitution in one family, no alterations in the opsin gene array were identified that could underlie the cone dysfunction. It is therefore possible that the cone dysfunction may have a genetic origin different from that of the dichromacy.
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Affiliation(s)
- Michel Michaelides
- Institute of Ophthalmology, University College London, London, United Kingdom
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7
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Abstract
Over the past decade, there has been an exponential increase in our knowledge of heritable eye conditions. Coincidentally, our ability to provide accurate genetic diagnoses has allowed appropriate counseling to patients and families. A summary of our current understanding of ocular genetics will prove useful to clinicians, researchers, and students as an introduction to the subject.
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Affiliation(s)
- Ian M MacDonald
- Department of Ophthalmology, University of Alberta, Edmonton, Alberta, Canada
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Abstract
The cone dystrophies comprise a heterogeneous group of disorders characterised by visual loss, abnormalities of colour vision, central scotomata, and a variable degree of nystagmus and photophobia. They may be stationary or progressive. The stationary cone dystrophies are better described as cone dysfunction syndromes since a dystrophy often describes a progressive process. These different syndromes encompass a wide range of clinical and psychophysical findings. The aim is to review current knowledge relating to the cone dysfunction syndromes, with discussion of the various phenotypes, the currently mapped genes, and genotype-phenotype relations. The cone dysfunction syndromes that will be discussed are complete and incomplete achromatopsia, oligocone trichromacy, cone monochromatism, blue cone monochromatism, and Bornholm eye disease. Disorders with a progressive cone dystrophy phenotype will not be discussed.
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Affiliation(s)
- M Michaelides
- Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
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Lee TKM, McTaggart KE, Sieving PA, Heckenlively JR, Levin AV, Greenberg J, Weleber RG, Tong PY, Anhalt EF, Powell BR, MacDonald IM. Clinical diagnoses that overlap with choroideremia. CANADIAN JOURNAL OF OPHTHALMOLOGY 2003; 38:364-72; quiz 372. [PMID: 12956277 DOI: 10.1016/s0008-4182(03)80047-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE To understand which clinical presentations suggest a diagnosis of choroideremia (CHM). METHODS Retrospective chart review. Included were patients for whom a clinical diagnosis of CHM was suggested, but either protein analysis or direct sequencing of the CHM gene could not confirm the diagnosis. Clinical presentation, family history and fundus photographs were reviewed. RESULTS We analyzed protein and DNA samples from members of more than 100 families in which at least 1 member had a clinical diagnosis of CHM. For 26 of these families, the clinical diagnosis of CHM could not be confirmed by laboratory analysis. Relevant clinical information was requested from the referring ophthalmologists so that alternative diagnoses could be considered. Sufficient information was provided for 13 of the 26 families. Four patients were reclassified as having retinitis pigmentosa (RP) from the clinical phenotype; only two clearly had X-linked inheritance. One patient had a syndrome including macular dystrophy, hearing loss, developmental delay and cerebral palsy. One patient was reclassified as having congenital stationary night blindness on the basis of an electronegative electroretinogram and a normal fundus. One patient had hearing loss suggesting Usher syndrome. One patient had signs consistent with cone-rod dystrophy (CRD). Five patients could not be reclassified on the basis of the clinical presentation. CONCLUSION RP, Usher syndrome and CRD are clinical phenotypes that may overlap with CHM. Clinical features that suggest CHM include severe chorioretinal atrophy with preservation of the macula, X-linked inheritance and retinal changes in a related female.
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Affiliation(s)
- Thomas K M Lee
- Department of Ophthalmology, University of Alberta, Edmonton, Alta
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Dryja TP. Molecular genetics of Oguchi disease, fundus albipunctatus, and other forms of stationary night blindness: LVII Edward Jackson Memorial Lecture. Am J Ophthalmol 2000; 130:547-63. [PMID: 11078833 DOI: 10.1016/s0002-9394(00)00737-6] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE To compare the clinical findings of the various forms of stationary night blindness caused by mutations in identified genes encoding proteins of photoreceptors or the retinal pigment epithelium. METHODS Review of the visual acuities, visual fields, fundi, dark-adaptation curves, and electroretinograms from patients with stationary night blindness caused by mutations in the genes RHO, GNAT1, PDE6B, RHOK, SAG, RDH5, and CACNA1F, respectively encoding rhodopsin, the alpha subunit of rod transducin, the beta subunit of rod cGMP-phosphodiesterase, rhodopsin kinase, arrestin, 11-cis retinol dehydrogenase, and a retinal L-type calcium channel. RESULTS In the evaluated forms of stationary night blindness, the time course of dark adaptation and the characteristics of the electroretinogram indicate that rod photoreceptors are present and that they function, although abnormally. In night blindness resulting from defects in rhodopsin, the alpha subunit of rod transducin, or the beta subunit of rod cGMP phosphodiesterase, rod photoreceptors respond only to light intensities far brighter than normal, and the sensitivity of rods to light is similar to that of normal individuals who are not dark adapted. In fundus albipunctatus and in Oguchi disease, the rod photoreceptors can achieve normal sensitivity to dim light but only after 2 or more hours of dark adaptation, compared with approximately 0.5 hours for normal individuals. In each of these forms of stationary night blindness, the poor rod sensitivity and the time course of dark adaptation correlate with the known or presumed physiologic abnormalities caused by the identified gene defects. Patients with some forms of stationary night blindness, such as fundus albipunctatus and Oguchi disease, may develop degeneration of the retina leading to severe loss of vision in later life. CONCLUSIONS The identification of the mutant genes causing forms of stationary night blindness refines the classification of these diseases and enhances our understanding of the underlying physiologic defects. Ophthalmologists must be aware that although these diseases are traditionally categorized as "stationary," some of them lead to reduced visual acuity or constricted visual fields, especially in older patients. Efforts to develop therapies for these diseases should concentrate on these more severe forms.
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Affiliation(s)
- T P Dryja
- Department of Ophthalmology, Harvard Medical School and the Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA
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Bech-Hansen NT, Naylor MJ, Maybaum TA, Sparkes RL, Koop B, Birch DG, Bergen AA, Prinsen CF, Polomeno RC, Gal A, Drack AV, Musarella MA, Jacobson SG, Young RS, Weleber RG. Mutations in NYX, encoding the leucine-rich proteoglycan nyctalopin, cause X-linked complete congenital stationary night blindness. Nat Genet 2000; 26:319-23. [PMID: 11062471 DOI: 10.1038/81619] [Citation(s) in RCA: 217] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
During development, visual photoreceptors, bipolar cells and other neurons establish connections within the retina enabling the eye to process visual images over approximately 7 log units of illumination. Within the retina, cells that respond to light increment and light decrement are separated into ON- and OFF-pathways. Hereditary diseases are known to disturb these retinal pathways, causing either progressive degeneration or stationary deficits. Congenital stationary night blindness (CSNB) is a group of stable retinal disorders that are characterized by abnormal night vision. Genetic subtypes of CSNB have been defined and different disease actions have been postulated. The molecular bases have been elucidated in several subtypes, providing a better understanding of the disease mechanisms and developmental retinal neurobiology. Here we have studied 22 families with 'complete' X-linked CSNB (CSNB1; MIM 310500; ref. 4) in which affected males have night blindness, some photopic vision loss and a defect of the ON-pathway. We have found 14 different mutations, including 1 founder mutation in 7 families from the United States, in a novel candidate gene, NYX. NYX, which encodes a glycosylphosphatidyl (GPI)-anchored protein called nyctalopin, is a new and unique member of the small leucine-rich proteoglycan (SLRP) family. The role of other SLRP proteins suggests that mutant nyctalopin disrupts developing retinal interconnections involving the ON-bipolar cells, leading to the visual losses seen in patients with complete CSNB.
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Affiliation(s)
- N T Bech-Hansen
- Department of Medical Genetics, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
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Stoddart KL, Jermak C, Nagaraja R, Schlessinger D, Bech-Hansen NT. Physical map covering a 2 Mb region in human xp11.3 distal to DX6849. Gene 1999; 227:111-6. [PMID: 9931462 DOI: 10.1016/s0378-1119(98)00564-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A 2Mb contig was constructed of yeast artificial chromosomes (YACs) and P1 artificial chromosomes (PACs), extending from DXS6849 to a new marker EC7034R, 1Mb distal to UBE1, within the p11.3 region of the human X chromosome. This contig, which has on average four-fold cloned coverage, was assembled using 37 markers, including 13 new sequence tagged sites (STSs) developed from YAC and PAC end-fragments, for an average inter-marker distance of 55kb. The inferred marker order predicted from SEGMAP analysis, STS content and cell hybrid data is Xpter-EC7034R-EC8058R-FB20E11-DXS7804-D XS8308-(DXS1264, DXS1055)-DXS1003-UBE1-(UHX), PCTK1)-DXS1364-DXS1266-DXS337-SYN1-DXS6 849-cen. One (TC)n dinucleotide sequence from an end-clone was identified and found to be polymorphic (48% heterozygosity). The contig is merged with published physical maps both in the distal and in the centromeric direction of Xp, and provides reagents to aid in the DNA sequencing and the finding of genes in this region of the human genome.
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Affiliation(s)
- K L Stoddart
- Department of Medical Genetics, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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Boycott KM, Pearce WG, Musarella MA, Weleber RG, Maybaum TA, Birch DG, Miyake Y, Young RS, Bech-Hansen NT. Evidence for genetic heterogeneity in X-linked congenital stationary night blindness. Am J Hum Genet 1998; 62:865-75. [PMID: 9529339 PMCID: PMC1377021 DOI: 10.1086/301781] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
X-linked congenital stationary night blindness (CSNB) is a nonprogressive retinal disorder characterized by disturbed or absent night vision; its clinical features may also include myopia, nystagmus, and impaired visual acuity. X-linked CSNB is clinically heterogeneous, and it may also be genetically heterogeneous. We have studied 32 families with X-linked CSNB, including 11 families with the complete form of CSNB and 21 families with the incomplete form of CSNB, to identify genetic-recombination events that would refine the location of the disease genes. Critical recombination events in the set of families with complete CSNB have localized a disease gene to the region between DXS556 and DXS8083, in Xp11.4-p11.3. Critical recombination events in the set of families with incomplete CSNB have localized a disease gene to the region between DXS722 and DXS8023, in Xp11.23. Further analysis of the incomplete-CSNB families, by means of disease-associated-haplotype construction, identified 17 families, of apparent Mennonite ancestry, that share portions of an ancestral chromosome. Results of this analysis refined the location of the gene for incomplete CSNB to the region between DXS722 and DXS255, a distance of 1.2 Mb. Genetic and clinical analyses of this set of 32 families with X-linked CSNB, together with the family studies reported in the literature, strongly suggest that two loci, one for complete (CSNB1) and one for incomplete (CSNB2) X-linked CSNB, can account for all reported mapping information.
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Affiliation(s)
- K M Boycott
- Department of Medical Genetics, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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MacDonald IM, Haney PM, Musarella MA. Summary of ocular genetic disorders and inherited systemic conditions with eye findings. Ophthalmic Genet 1998; 19:1-17. [PMID: 9587925 DOI: 10.1076/opge.19.1.1.2181] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Of the close to 10,000 known inherited disorders that affect humankind, a disproportionately high number affect the eye. The total number of genes responsible for the normal structure, function, and differentiation of the eye is unknown, but the list of these genes is rapidly and constantly growing. The objective of this paper is to provide a current list of mapped and/or cloned human eye genes that are responsible for inherited diseases of the eye. The ophthalmologist should be aware of recent advances in molecular technology which have resulted in significant progress towards the identification of these genes. The implications of this new knowledge will be discussed herein.
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Affiliation(s)
- I M MacDonald
- Department of Ophthalmology, University of Alberta, Canada
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Yamamoto S, Khani SC, Berson EL, Dryja TP. Evaluation of the rhodopsin kinase gene in patients with retinitis pigmentosa. Exp Eye Res 1997; 65:249-53. [PMID: 9268593 DOI: 10.1006/exer.1997.9998] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We explored the possibility that defects in the rhodopsin kinase gene might cause retinitis pigmentosa (RP) by evaluating 160 unrelated cases with dominant RP and 151 unrelated cases with recessive RP. One of five missense changes was discovered in each of six cases of dominant RP, but none of the missense changes cosegregated with disease among relatives. Heterozygous missense changes were found in two cases of recessive RP, and a heterozygous frameshift mutation was found in one additional case of recessive RP. Although the same DNA sequence alterations could be found heterozygously in the only affected sibling of each index case of recessive RP, no defect could be found in the other allele. Hence, none of the changes found in the cases of dominant or recessive RP was proven to be a cause of RP. The data indicate that defects in the rhodopsin kinase gene causing RP are either rare or nonexistent.
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Affiliation(s)
- S Yamamoto
- Ocular Molecular Genetics Institute, Harvard Medical School, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA
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Bergen AA, ten Brink JB, Riemslag F, Schuurman EJ, Meire F, Tijmes N, de Jong PT. Conclusive evidence for a distinct congenital stationary night blindness locus in Xp21.1. J Med Genet 1996; 33:869-72. [PMID: 8933343 PMCID: PMC1050769 DOI: 10.1136/jmg.33.10.869] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
X linked congenital stationary night blindness (CSNBX) is a non-progressive retinal disorder characterised by decreased visual acuity and disturbance of night vision. CSNBX appears to be not only clinically but also genetically heterogeneous. On studying a single large family, we recently suggested the presence of a distinct locus for CSNBX in Xp21.1. Here, we describe the results of a linkage analysis in another large CSNBX family, which confirms this finding. Thus, the data presented here provide conclusive evidence for a distinct CSNBX locus in Xp21.1, closely linked to the X linked retinitis pigmentosa type 3 gene. The results combined with other published results indicate the order Xpter-DXS451-DMD-DYS1-(DXS1110, CSNBX1, XLRP3)-DXS7-(CSNBX2, XLRP2)-DXS14-Xcen.
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Affiliation(s)
- A A Bergen
- Department of Ophthalmogenetics, The Netherlands Ophthalmic Research Institute, Amsterdam, The Netherlands
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Jensen H, Warburg M, Sjö O, Schwartz M. Duchenne muscular dystrophy: negative electroretinograms and normal dark adaptation. Reappraisal of assignment of X linked incomplete congenital stationary night blindness. J Med Genet 1995; 32:348-51. [PMID: 7616540 PMCID: PMC1050428 DOI: 10.1136/jmg.32.5.348] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Aland Island eye disease (AIED) and X linked congenital stationary night blindness (CSNB) have been mapped to Xp11.3. Patients have been described with deletions of the Duchenne muscular dystrophy (DMD) gene who also had a negative electroretinogram (ERG) similar to that seen in patients with CSNB and AIED. This seems to confirm that some cases of AIED and CSNB map to Xp21. We examined 16 boys with DMD/BMD (Becker muscular dystrophy) of whom 10 had negative ERGs, eight of them having deletions downstream from exon 44. Normal dark adaptation thresholds were observed in all patients and there were no anomalous visual functions. Hence, CSNB cannot be assigned to Xp21 and negative ERG in DMD/BMD is not associated with eye disease. Six boys with DMD/BMD had normal ERGs. We speculate that a retinal or glial dystrophin may be truncated or absent in the boys with negative ERGs.
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Affiliation(s)
- H Jensen
- Division of Paediatric Ophthalmology and Handicaps, Gentofte Hospital, University of Copenhagen, Denmark
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Hawksworth NR, Headland S, Good P, Thomas NS, Clarke A. Aland island eye disease: clinical and electrophysiological studies of a Welsh family. Br J Ophthalmol 1995; 79:424-30. [PMID: 7612552 PMCID: PMC505128 DOI: 10.1136/bjo.79.5.424] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Clinical and molecular genetic studies were performed on a single, large, white family, in which congenital nystagmus and moderate to high refractive error segregated as a sex linked trait with manifestation in some female carriers. In this family, affected males demonstrate myopia, but a high proportion of female carriers, and some of the possibly affected males, show hypermetropia. Clinical ophthalmic examination and electrodiagnostic studies of retinal function were fully compatible with a diagnosis of either incomplete congenital stationary night blindness or of Aland island eye disease. Previous studies have mapped both disorders to the proximal short arm of the X chromosome: our molecular studies support this localisation. Incomplete congenital stationary nightblindness and Aland Island eye disease could be considered as a single entity.
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Affiliation(s)
- N R Hawksworth
- Department of Ophthalmology, University Hospital of Wales, Cardiff
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Berger W, van Duijnhoven G, Pinckers A, Smits A, Ropers HH, Cremers F. Linkage analysis in a Dutch family with X-linked recessive congenital stationary night blindness (XL-CSNB). Hum Genet 1995; 95:67-70. [PMID: 7814029 DOI: 10.1007/bf00225077] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Linkage analysis has been performed in a large Dutch pedigree with X-linked recessive congenital stationary night blindness (CSNB) by utilizing 16 DNA markers from the proximal short arm of the human X chromosome (Xp21.1-11.2). Thirteen polymorphic markers are at least partially informative and have enabled pairwise and multipoint linkage analysis. For three loci, i.e. DXS228, the monoamine oxidase B gene and the Norrie disease gene (NDG), multipoint linkage studies have yielded maximum lod scores of > 3.0 at a recombination fraction of zero. Analysis of recombination events has enabled us to rule out the possibility that the underlying defect in this family is allelic to RP3; the gene defect could also be excluded from the proximal part of the region known to carry RP2. Linkage data are consistent with a possible involvement of the NDG but mutations in the open reading frame of this gene have not been found.
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Affiliation(s)
- W Berger
- Department of Human Genetics, University Hospital Nijmegen, The Netherlands
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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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Acland GM, Blanton SH, Hershfield B, Aguirre GD. XLPRA: a canine retinal degeneration inherited as an X-linked trait. AMERICAN JOURNAL OF MEDICAL GENETICS 1994; 52:27-33. [PMID: 7977457 DOI: 10.1002/ajmg.1320520106] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Breeding studies are reported of a previously undescribed hereditary retinal degeneration identified in the Siberian Husky breed of dog. This disorder clinically resembles the previously reported autosomal recessive canine hereditary retinal degenerations collectively termed progressive retinal atrophy (PRA). However, the pedigree of the propositus, a male Siberian Husky, exhibited an X-linked pattern of transmission. This dog was outcrossed to three phenotypically normal female laboratory Beagles and two of their F1 daughters were bred to a phenotypically normal male Beagle, producing affected males in the F2 generation. Subsequent inbreedings produced further affected males and affected females as well. X-linked transmission was established by exclusion of alternative modes of inheritance and, consequently, the disease has been termed X-linked progressive retinal atrophy (XLPRA). This is the first reported X-linked retinal degeneration in an animal. Because of the many similarities of PRA in dogs to retinitis pigmentosa (RP) in humans, this new disease may not only represent the first animal model of X-linked RP (XLRP) but may well be a true homolog of one of the XLRP loci (RP2, RP3, RP6). It is the first retinal degeneration in dogs that can be assigned to an identified canine chromosome, and the first for which linkage mapping offers a realistic approach to proceed by positional cloning towards identifying the responsible gene locus.
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Affiliation(s)
- G M Acland
- James A. Baker Institute for Animal Health, Cornell University College of Veterinary Medicine, Ithaca, New York 14853
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22
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Bergen AA, Kestelyn P, Leys M, Meire F. Identification of a key recombinant which assigns the incomplete congenital stationary night blindness gene proximal to MAOB. J Med Genet 1994; 31:580-2. [PMID: 7966198 PMCID: PMC1049985 DOI: 10.1136/jmg.31.7.580] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The gene for complete congenital stationary night blindness (CSNB1) has been assigned to the Xp11.3 region. However, little evidence has been provided for the assignment of the incomplete congenital stationary night blindness gene (CSNB2). Here we present the clinical and molecular data from a CSNB2 family which show a key recombinant assigning the CSNB2 gene proximal to MAOB.
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Affiliation(s)
- A A Bergen
- The Netherlands Ophthalmic Research Institute, Amsterdam
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23
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Sigesmund DA, Weleber RG, Pillers DA, Westall CA, Panton CM, Powell BR, Héon E, Murphey WH, Musarella MA, Ray PN. Characterization of the ocular phenotype of Duchenne and Becker muscular dystrophy. Ophthalmology 1994; 101:856-65. [PMID: 8190471 DOI: 10.1016/s0161-6420(13)31249-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
PURPOSE Dystrophin, the Duchenne muscular dystrophy gene product, has been localized to the outer plexiform layer of normal human retina. The purpose of this study is to define completely the ocular phenotype associated with mutations at Xp21, the Duchenne muscular dystrophy gene locus. METHODS Twenty-one patients with a diagnosis of Duchenne muscular dystrophy and five patients with Becker muscular dystrophy had ophthalmologic examinations, including electroretinograms (ERGs). Electroretinogram results were correlated with respect to patient DNA analysis. RESULTS Twenty-three (88%) patients had reduced scotopic b-wave amplitudes to bright-white flash stimulus, including nine with negative-shaped ERGs. Rod-isolated responses were reduced or not recordable above noise in 14 (67%) patients. Most isolated cone responses (92%) were normal. Flicker amplitudes were reduced in seven patients. Two of these patients with proximal (5' end) deletions had normal scotopic b-waves to dim blue and bright-white flash stimulus. Patients with deletions toward the middle of the gene had greater reductions in their scotopic b-wave amplitudes than patients with deletions located toward the 5' end. Most patients had normal color vision, extraocular muscle function, and Snellen visual acuity. Increased macular pigmentation was seen in 16 patients with Duchenne muscular dystrophy. CONCLUSION Most patients with Duchenne or Becker muscular dystrophy have evidence of abnormal scotopic ERGs. Patients with deletions in the central region of the gene had the most severe ERG changes. This study supports previous suggestions that dystrophin may play a role in retinal neurotransmission. The presence of increased macular pigmentation and normal photopic ERGs distinguishes patients with Duchenne muscular dystrophy mutations from other X-linked retinal disorders with negative-shaped ERGs.
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Affiliation(s)
- D A Sigesmund
- Department of Ophthalmology, Hospital for Sick Children, Toronto, Ontario
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24
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Glass IA, Good P, Coleman MP, Fullwood P, Giles MG, Lindsay S, Nemeth AH, Davies KE, Willshaw HA, Fielder A. Genetic mapping of a cone and rod dysfunction (Aland Island eye disease) to the proximal short arm of the human X chromosome. J Med Genet 1993; 30:1044-50. [PMID: 7907666 PMCID: PMC1016646 DOI: 10.1136/jmg.30.12.1044] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A five generation family with an X linked ocular disorder has been investigated. The major clinical features were reduced visual acuity, nystagmus, and myopia. Although impaired night vision was not a symptom, using psychophysical and electrophysiological testing both rod and cone function were found to be abnormal in all affected males. No abnormality was detected in carrier females. Gene location studies showed X linked transmission of a gene that maps to proximal Xp11. The findings observed in this cohort are similar to those previously reported in both congenital stationary night blindness type 2 (CSNB2) and Aland Island eye disease (AIED). This study addresses whether CSNB2 and AIED are a single entity or whether the latter is a subset of the former.
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Affiliation(s)
- I A Glass
- Department of Pediatrics, School of Medicine, University of California, San Francisco 94143
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25
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Shastry BS. Recent developments in certain X-linked genetic eye disorders. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1182:119-27. [PMID: 8357842 DOI: 10.1016/0925-4439(93)90131-j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Over the past few years, genetic diseases of the ocular system have become very active and fast-growing research areas in the vision field. The rapid development of the recombinant DNA techniques together with somatic cell genetics, during the last two decades has fueled this progress. As a result, many genetic disease genes have been localized in the human chromosome and several of them have been isolated and characterized. These and other studies have profoundly enriched our basic understanding of genetic eye disorders. Although gene replacement therapy, prenatal diagnosis and carrier detection have not been extensively tried for genetic eye diseases, such attempts will now be feasible. Molecular analyses made it clear that there are many challenging problems that need attention. This report highlights some of these initial developments, particularly on the X-linked major genetic eye diseases. In order to help the beginners and general audience, a brief description of the clinical pathology and the molecular probes used to locate the genetic defects of certain disorders are presented. Disorders are arranged according to their linkage from telomere to telomere on the chromosome to give a coherent structure. It is hoped that this information is useful and of general interest for the beginners, established investigators and ophthalmologists.
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Affiliation(s)
- B S Shastry
- Eye Research Institute of Oakland University, Rochester, MI 48309-4401
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26
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Pillers DA, Bulman DE, Weleber RG, Sigesmund DA, Musarella MA, Powell BR, Murphey WH, Westall C, Panton C, Becker LE. Dystrophin expression in the human retina is required for normal function as defined by electroretinography. Nat Genet 1993; 4:82-6. [PMID: 8513332 DOI: 10.1038/ng0593-82] [Citation(s) in RCA: 112] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We have studied retinal function by electroretinography in five Becker and six Duchenne muscular dystrophy patients. All had abnormal electroretinograms with a markedly reduced amplitude for the b-wave in the dark-adapted state. Using three antisera raised to different domains of dystrophin, we identified dystrophin in the outer plexiform layer of human retina. The retinal dystrophin is present in multiple isoforms as the result of alternative splicing. The localization of dystrophin to the outer plexiform layer coincident with the abnormal b-wave suggests that dystrophin is required for normal retinal electrophysiology.
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Affiliation(s)
- D A Pillers
- Department of Pediatrics, Oregon Health Sciences University, Portland 97201
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27
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Dry KL, Van Dorp DB, Aldred MA, Brown J, Hardwick LJ, Wright AF. Linkage analysis in a family with complete type congenital stationary night blindness with and without myopia. Clin Genet 1993; 43:250-4. [PMID: 8375106 DOI: 10.1111/j.1399-0004.1993.tb03812.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A family is described with X-linked congenital stationary night blindness of the complete type (CSNB1) in which clinical variation between affected males resulted in diagnostic difficulties. In two affected male cousins, one had congenital nystagmus and myopia, while the other was initially thought to have retinitis pigmentosa with optic atrophy and was hyperopic. The diagnosis of X-linked congenital stationary night blindness was established by clinical, psychophysical and electrophysiological criteria, and DNA markers flanking the CSNB1 locus were analysed in the family. The results show that both affected males have inherited the same haplotype from their carrier mothers, excluding the possibility that a myopia gene in linkage disequilibrium with CSNB1 has recombined with this locus.
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Affiliation(s)
- K L Dry
- MRC Human Genetics Unit, Western General Hospital, Edinburgh, UK
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28
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Berger W, Meindl A, de Leeuw B, de Roos A, van de Pol TJ, Meitinger T, van der Velde-Visser SD, Achatz H, Geurts van Kessel A, Cremers FP. Generation and characterization of radiation reduced cell hybrids and isolation of probes from the proximal short arm of the human X chromosome. Hum Genet 1992; 90:243-6. [PMID: 1487237 DOI: 10.1007/bf00220070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Employing a modified Goss-Harris irradiation fusion protocol, we have generated a panel of somatic cell hybrids containing various overlapping fragments of the Xcen-Xp11.4 interval. This region of the human X chromosome is known to carry genes for several hereditary eye diseases including retinitis pigmentosa (RP2), congenital stationary night blindness (CSNB-1) and Norrie disease. These hybrid cell lines were employed to isolate 17 new DNA probes by making use of the Alu polymerase chain reaction (PCR) method and subsequent cloning of the PCR products in a plasmid vector. With these probes, we have characterized two previously described microdeletions spanning the Norrie locus; these deletions have enabled us to subdivide the Xp11.4-p11.3 region into three defined intervals.
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Affiliation(s)
- W Berger
- Department of Human Genetics, University Hospital Nijmegen, The Netherlands
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29
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Aldred MA, Dry KL, Sharp DM, Van Dorp DB, Brown J, Hardwick LJ, Lester DH, Pryde FE, Teague PW, Jay M. Linkage analysis in X-linked congenital stationary night blindness. Genomics 1992; 14:99-104. [PMID: 1427834 DOI: 10.1016/s0888-7543(05)80289-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
X-linked congenital stationary night blindness (XL-CSNB) is a nonprogressive disorder of the retina, characterized by night blindness, reduced visual acuity, and myopia. Previous studies have localized the CSNB1 locus to the region between OTC and TIMP on the short arm of the X chromosome. We have carried out linkage studies in three XL-CSNB families that could not be classified as either complete or incomplete CSNB on the criteria suggested by Miyake et al. (1986. Arch. Ophthalmol. 104: 1013-1020). We used markers for the DXS538, DMD, OTC, MAOA, DXS426, and TIMP loci. Two-point analyses show that there is close linkage between CSNB and MAOA (theta max = 0.05, Zmax = 3.39), DXS426 (theta max = 0.06, Zmax = 2.42), and TIMP (theta max = 0.07, Zmax = 2.04). Two multiply informative crossovers are consistent with CSNB lying proximal to MAOA and distal to DXS426, respectively. Multipoint analysis supports this localization, giving the most likely order as DMD-17 cM-MAOA-7.5 cM-CSNB-7.5 cM-DXS426/TIMP-cen, and thus refines the localization of CSNB.
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Affiliation(s)
- M A Aldred
- MRC Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
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30
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Lindsay S, Inglehearn CF, Curtis A, Bhattacharya S. Molecular genetics of inherited retinal degenerations. Curr Opin Genet Dev 1992; 2:459-66. [PMID: 1504622 DOI: 10.1016/s0959-437x(05)80158-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
There has recently been substantial progress in categorizing the vast range of human retinal degeneration phenotypes. A molecular approach has assigned chromosomal locations for approximately a dozen such diseases and has identified four of the genes involved.
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Affiliation(s)
- S Lindsay
- Molecular Genetics Unit Division of Human Genetics, University of Newcastle upon Tyne, UK
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31
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Ruttum MS, Lewandowski MF, Bateman JB. Affected females in X-linked congenital stationary night blindness. Ophthalmology 1992; 99:747-52. [PMID: 1594221 DOI: 10.1016/s0161-6420(92)31902-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Most heterozygous (carrier) females in families with X-linked congenital stationary night blindness are asymptomatic. Several anecdotal cases of manifesting females in X-linked congenital stationary night blindness have been reported, but few clinical details are available. The authors report clinical, electroretinographic, and dark adaptation studies of four affected females from a five-generation family with X-linked congenital stationary night blindness. Each of the manifesting females was the daughter of a different, asymptomatic, carrier mother. None of the 14 daughters of the 9 affected males showed signs or symptoms of congenital stationary night blindness. Uneven X-chromosomal lyonization is the most likely reason for these females manifesting this X-linked disorder.
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Affiliation(s)
- M S Ruttum
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee
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32
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Bech-Hansen NT, Moore BJ, Pearce WG. Mapping of locus for X-linked congenital stationary night blindness (CSNB1) proximal to DXS7. Genomics 1992; 12:409-11. [PMID: 1740347 DOI: 10.1016/0888-7543(92)90394-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A recombinant chromosome in a male affected with X-linked congenital stationary night blindness (CSNB1) provides new information on the location of the CSNB1 locus. A four-generation family with five males affected with X-linked CSNB was analyzed with five polymorphic markers for four X-chromosome loci spanning the region OTC (Xp21.1) to DXS255 (Xp11.22). Four of the males inherited the same X chromosome; one male inherited a chromosome that from OTC to DXS7, inclusive, was derived from the normal X chromosome of his unaffected grandfather and that from a location between DXS7 and DXS426 proximally was derived from the chromosome carrying the CSNB1 locus. This recombinant maps the CSNB1 locus in this family to a region on the short arm of the X chromosome proximal to the DXS7 locus.
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Affiliation(s)
- N T Bech-Hansen
- Department of Paediatrics, Alberta Children's Hospital, Calgary, Canada
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33
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Abstract
Increasing awareness of the role of genetic factors in the causation of many human eye diseases has made ocular genetics one of the fastest growing areas of ophthalmology. The objective of this paper is to present the basic principles of gene mapping and their application to ophthalmology. The techniques used to map the genome are reviewed with emphasis placed on molecular genetics. The advances in this area have already provided the major impetus to the areas of diagnosis and prevention of some genetic eye disorders. Tables are presented that list the autosomal, X-linked and mitochondrial assignment of eye genes and disorders with ocular involvement.
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Affiliation(s)
- M A Musarella
- Hospital for Sick Children, Department of Ophthalmology, Toronto, Ontario, Canada
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34
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Coleman MP, Murray JC, Willard HF, Nolan KF, Reid KB, Blake DJ, Lindsay S, Bhattacharya SS, Wright A, Davies KE. Genetic and physical mapping around the properdin P gene. Genomics 1991; 11:991-6. [PMID: 1783405 DOI: 10.1016/0888-7543(91)90024-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A CA repeat has been found on the human X chromosome within 16 kb of the gene encoding properdin P factor (PFC) and has been shown to be a highly informative marker. Two more polymorphic CA repeats were found in a cosmid containing DXS228. The CA repeats, and other markers from proximal Xp, were mapped genetically in CEPH families and the likely order of markers was established as Xpter-(DXS7, MAO-A, DXS228)-(PFC, DXS426)-(TIMP, OATL1)-DXS255-Xcen. This places PFC in the region Xp11.3-Xp11.23, thus refining previous in situ hybridization data. Two yeast artificial chromosomes (YACs) (440 and 390 kb) contain both PFC and DXS426, and one of them (440 kb) also contains TIMP. This confirms the genetic order TIMP-(PFC, DXS426). PFC and TIMP are located on the same 100-kb SalI/PvuI fragment of the 440-kb YAC. Given the genetic orientation of TIMP and (PFC, DXS426), this YAC can now serve as a starting point for directional walking toward disease genes located in Xp11.3-Xp11.2 such as retinitis pigmentosa (RP2) and Wiskott-Aldrich syndrome.
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Affiliation(s)
- M P Coleman
- Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, England
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35
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Abstract
A large Danish family with Aland Island eye disease (AIED) was studied by linkage analysis using 16 polymorphic DNA markers covering the whole X chromosome. Positive lod scores were found for marker loci at the proximal part of the short arm of the X chromosome, DXS255 and TIMP (Zmax = 3.93 and 3.18 at theta = 0.0), suggesting an assignment of the locus for AIED to this part of the X chromosome. Recombination was observed with the locus DXS7 as well as with other loci distal to DXS7. These results are not in agreement with the deletion presented previously by D-A. M. Pillers et al. (1990, Am. J. Med. Genet. 36: 23-28), which mapped AIED to Xp21.
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Affiliation(s)
- M Schwartz
- Department of Pediatrics, University Hospital, Copenhagen, Denmark
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36
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Gutmann DH, Brooks ML, Emanuel BS, McDonald-McGinn DM, Zackai EH. Congenital nystagmus in a (46,XX/45,X) mosaic woman from a family with X-linked congenital nystagmus. AMERICAN JOURNAL OF MEDICAL GENETICS 1991; 39:167-9. [PMID: 2063919 DOI: 10.1002/ajmg.1320390210] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
X-linked congenital nystagmus is a rare disorder in which affected males manifest binocular uniplanar nystagmus with associated head oscillation. In the families previously reported, affected females have been described. We report on a multigeneration family with X-linked congenital nystagmus with an affected woman. She was a (46,XX/45,X) mosaic. Magnetic resonance images of the brain of affected individuals were normal.
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Affiliation(s)
- D H Gutmann
- Department of Neurology, Hospital, University of Pennsylvania, Philadelphia
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37
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Abstract
The pace of localization and characterization of genes affected in human genetic disorders is quickening. Many important genes were localized or characterized recently: genes for in cystic fibrosis, NF-2, Marfan's syndrome and xeroderma pigmentosum, to name a few. Also, in the past 15 months, the CFTR gene affected in cystic fibrosis has been isolated, the first disease gene to be isolated without use of previous cytogenetic clues, such as deletions or translocations in sporadic cases. Other examples should follow, although we have been disappointed to date by the difficulties encountered in the isolation of Huntington's disease gene which was localized a number of years ago to distal chromosome 4p. It is still very difficult to isolate a disease gene without critical cytogenetic information. New improved techniques for finding the desired expressed sequences in a large cloned segment of human DNA are needed. Our ability to find mutant alleles of a given sequence has expanded greatly with the recent technical advances in denaturing gradient gel electrophoresis, chemical cleavage, and single-stranded conformational electrophoresis. One would predict that information derived from the human genome project will have a major impact upon the isolation of further disease genes. As whole regions of human chromosomes or indeed entire chromosomes are physically mapped and cloned as continuous, overlapping YACs (yeast artificial chromosomes), isolation of disease genes will become easier and easier.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- C D Boehm
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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