Linkage analysis of X linked retinitis pigmentosa in the Irish population.

Farrar, G. Jane; Geraghty, Michael T.; Moloney, Jennifer; McConnell, David J.; Humphries, Peter

doi:10.1136/jmg.25.4.222

Cited by 9 publications

(4 citation statements)

References 19 publications

(1 reference statement)

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“…However, as suggested by , this gene location was not secure, because in one case the exclusion of heterozygous status from a female with normal ophthalmological findings was not reliable and in the other case the crossover was in doubt due to the subsequent finding of nonpaternity. The linkage analyses performed by Bhattacharya et al (1984), Mukai et al (1985) and Farrar et al (1988) did not suggest whether the XLRP locus is centromeric to DXS7 or telomeric to DXS7. Non-allelic heterogeneity has not been confirmed by any of the previous reports.…”

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confidence: 89%

Non‐allelic mutations in X‐linked retinitis pigmentosa

et al. 1989

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Non‐allelic mutations in X‐linked retinitis pigmentosa

et al. 1989

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“…However, Friedrich et al (1985) inferred that XLRP was proximal to L1.28 on the basis of 3point crosses informative for a C-banding polymorphism and L1.28. In a study based largely on a single large Irish pedigree displaying typical XLRP (Farrar et al 1988), significant linkage was demonstrated between XLRP and both 754 and L1.28 (6= 3.855, Z = 0; B = 3.445, Z = 0 respectively), suggesting a probable location for XLRP distal to L1.28.…”

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confidence: 99%

Retinitis pigmentosa: genetic mapping in X‐linked and autosomal forms of the disease

et al. 1990

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Retinitis pigmentosa (RP) is an hereditary degenerative disease of the retina and a major cause of visual impairment, prevalence estimates ranging from 1 in 3000 to 1 in 7000. The condition may segregate as an autosomal dominant, autosomal recessive or an X‐linked recessive trait and it may also occur on a sporadic basis in up to 50% of cases. In the autosomal dominant form, close linkage to the DNA marker C17 (D3S47) was recently established in a large family of Irish origin displaying early‐onset disease (McWilliam et al. 1989), multipoint analysis indicating the gene for rhodopsin as a likely candidate (Farrar et al. 1990). In that gene, a C→A transversion in codon 23, resulting in a proline→histidine substitution has now been identified in 17 of 148 unrelated ADRP patients in the United States (Dryja et al. 1990). This mutation is absent however in the original Irish pedigree (it is also absent in 21 other dominant Irish pedigrees, representing approximately 70% of the estimated ADRP population) indicating that another mutation, either in rhodopsin itself, or in a gene very closely linked to rhodopsin is responsible for the disease in that family. Analysis of other dominant pedigrees using the C17 and/or rhodopsin probes has indicated either tight linkage (Bhattacharya, Personal Communication), looser linkage, possibly indicative of a second locus on 3q (Olsson et al. 1990) or no linkage (Farrar et al. 1990, Blanton et al. 1990, Inglehearn et al. 1990). Extensive genetic heterogeneity thus exists in the autosomal dominant form of this disease, and in the light of these new observations, earlier tentative evidence for linkage of ADRP to the Rhesus locus on chromosome I will be re‐evaluated. A locus for type II Usher syndrome (classical RP combined with congenital pedial deafness, and normal vestibular function) has now been established on the long arm of chromosome 1 (Kimberling et al. 1990). Type I Usher families, in which hearing loss is more profound and vestibular function absent, do not segregate with the same chromosome 1q markers, indicating the existence of another, as yet unlocated gene. In the X‐linked form of the disease, two genes, XLRP2 and XLRP3, have been located on the proximal short arm of the X chromosome using a combination of physical and linkage mapping techniques, and there is some evidence to suggest a possible third locus more distally located. Advances thus being made, in the localization, isolation and characterization of RP‐causing genes, are likely radically to extend our knowledge of the molecular pathology of this prevalent group of conditions over the next few years.

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“…The apparent absence of X-linked retinal degenerations in animals is particularly striking given the number of retinal disorders mapped to the human X chromosome. The latter includes Aland Island eye disease [Alitalo et al, 1990;Davies et al, 1991;Schwartz and Rosenberg, 19911, choroideremia [van den Hurk et al, 1991, 19921, cone dystrophy 1 [Bartley et al, 19891, congenital stationary night blindness [Bech-Hansen et al, 1990Li et al, 1991;Musarella et al, 1989a1, defects in the cone long-wave opsin genes LNathans et al, 19891, Oregon eye disease [Pillers et al, 1990;Weleber et al, 1989;Davies et al, 19911, and three forms of retinitis pigmentosa: RP2 [Bhattacharya et al, 1984;Denton et al, 1988;Farrar et al, 1988;Friedrich et al, 1985;Mukai et al, 1985;Wright et al, 19871, RP3 [de Saint-Basile et al, 1988;Francke et al, 1985;Musarella et al, 1988Musarella et al, , 1989bNussbaum et al, 1985;Wirth et al, 19881, and RP6 [Davies et al, 1991;Musarella et al, 1988Musarella et al, , 1990Ott et al, 19901. Canine inherited retinal degenerations are collectively termed progressive retinal atrophy (PRA). Clinical recognition of differences among the forms of PRA typical of different pure breeds of dog has aided the definition of several genetically distinct disorders.…”

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XLPRA: A canine retinal degeneration inherited as an X‐linked trait

et al. 1994

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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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Linkage analysis of X linked retinitis pigmentosa in the Irish population.

Cited by 9 publications

References 19 publications

Non‐allelic mutations in X‐linked retinitis pigmentosa

Non‐allelic mutations in X‐linked retinitis pigmentosa

Retinitis pigmentosa: genetic mapping in X‐linked and autosomal forms of the disease

XLPRA: A canine retinal degeneration inherited as an X‐linked trait

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