Analysis of linkage relationships of X-linked retinitis pigmentosa with the following Xp loci: L1.28, OTC, 754, XJ-1.1, pERT87, and C7

Abstract

A number of variants of X-linked retinitis pigmentosa (XLRP) have been described. In one variant, listed in the McKusick (McK) catalogue (McKusick 1983) as entry no. 30320, the heterozygotes exhibit a golden metallic or tapetal reflex. Three large pedigrees segregating for XLRP with the characteristic tapetal reflex in the heterozygotes were examined, and the linkage between the XLRP locus and Xp loci, L1.28, OTC, 754, XJ-1.1, pERT87 and C7 was measured. The strongest linkage was found to be between the XLRP locus and OTC. In addition, recombinational evidence drawn from the three pedigrees suggests that the XLRP locus is distal to L1.28 and proximal to 754. This putative location of the XLRP gene between L1.28 and 754 taken together with the tight linkage to OTC, a locus already located between L1.28 and 754, leads us to propose a gene order of centromere-L1.28-OTC/XLRP-754-telomere.

A family with RP3 type of X-linked retinitis pigmentosa: an association with ciliary abnormalities

“…OTC was therefore used to estimate risks in those "at risk" females showing no clinical signs of the disease, but that remain at risk because of the reduced penetrance of the carrier state, particularly in women under 40 years of age. Assuming a conservative figure of 3% (0.03) recombination between RP3 and OTC (Denton et al 1986), two "at risk" females are at a high risk (97%) of being carriers, whereas two others (IV-7, IV-13) are at a low risk (3%). This illustrates the advantage of supplementing clinical examinations with DNA probe information in diagnosis of the XLRP-cartier state.…”

Genetic mapping of loci for X‐linked retinitis pigmentosa

“…Linkage analysis in families with XLRP has shown conflicting results regarding the location of the disease locus, suggestive of heterogeneity. Taken together, several reports have produced results indicating two loci on the short arm of the X-chromosome (Nussbaum et al 1985, Wright et al 1987, Denton et al 1988, Wirth et al 1988, Chen et al 1989a, 1989b. for a review see Humphries et a].…”

Multipoint linkage analysis and heterogeneity testing in 20 X-linked retinitis pigmentosa families

“…Since this first report on the assignment of the X LRP gene, other investigators have confirmed this mapping to X p ll.3 (Mukai et al, 1985;Friedrich et al, 1985;Wright et al, 1987). However, further linkage studies on numerous other families generally support an additional site for X LRP at Xp21 (RP3) (Nussbaum et al, 1985;Francke et al, 1985;Denton et al, 1988;Wirth et al, 1988;Musarella et al, 1988). Further support for an Xp21 locus for XLR P comes from descriptions of two rare male patients with multiple phenotypes including X LRP and deletions in the Xp21 region (Francke et al, 1985;de Saint-Basile et al, 1988).…”