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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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2
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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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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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Tremblay F, Laroche RG, De Becker I. The electroretinographic diagnosis of the incomplete form of congenital stationary night blindness. Vision Res 1995; 35:2383-93. [PMID: 7571473 DOI: 10.1016/0042-6989(95)00006-l] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Fifteen patients with the incomplete form of congenital stationary night blindness (iCSNB) were reviewed to better characterize their electroretinographic (ERG) findings in view of differential diagnosis with other retinal conditions also presenting with negative bright-flash ERG responses. In all 15 patients, in dark-adapted conditions, the bright-flash ERG response had a normal a-wave followed by a subnormal b-wave. Oscillatory potentials (OPs) observed on the ascending limb of the b-wave, although delayed in implicit time, were of large amplitude. The response to a long-wavelength stimulus showed cone-related components and some well-delineated OPs. On the other hand, the photopically elicited cone responses were strongly abnormal, with a subnormal a-wave followed by a barely recordable b-wave. No OPs could be elicited under photopic conditions. The cone related components and the OP characteristics clearly distinguish iCSNB from the complete form of CSNB and other retinal conditions presenting with minimal fundus abnormalities but with negative bright-flash ERG responses, such as found in Duchenne muscular dystrophy and Aland Island eye disease. The severely abnormal post-synaptic components in the photopic recordings contrast with the well-differentiated cone activity evoked in scotopic conditions. We propose a cone system that does not respond optimally under the normal operating range (photopic) but rather under mesopic or scotopic conditions. In spite of the severe cone-ERG deficits, visual acuity was only slightly reduced. We propose that the defect, which interferes marginally with the neuronal flow of information, lies in the structures responsible for the building of the b-wave.
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Affiliation(s)
- F Tremblay
- Department of Ophthalmology, Dalhousie University, Halifax, Nova Scotia, Canada
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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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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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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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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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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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