Dataset Information

Linkage disequilibrium and physical mapping of X-linked juvenile retinoschisis.

ABSTRACT: X-linked juvenile retinoschisis (RS) is a recessively inherited disorder resulting in poor visual acuity. Affected males typically show retinal degeneration and intraretinal splitting. The prevalence of RS is 1:15,000-1:30,000. Elsewhere we have mapped the RS gene between the markers DXS43 and DXS274 in Xp22.1-p22.2. To narrow the RS region, we analyzed 31 Finnish RS families with the markers DXS418, DXS999, DXS7161, and DXS365 and a new polymorphic microsatellite marker, HYAT1. Multipoint linkage analysis allowed us to localize the RS gene between the markers DXS418 and DXS7161 (LOD score = 31.3). We have covered this region with nine YAC clones. On the basis of the sizes of the YACs, sequence-tagged site (STS) content mapping, and restriction mapping, the physical distance between DXS418 and DXS7161 is approximately 0.9 Mb. A total of five potential CpG islands could be identified. For haplotype analysis, eight additional Finnish RS families were analyzed with the markers DXS1195, DXS418, HYAT1, DXS999, DXS7161, and DXS365. On the basis of the linkage-disequilibrium data that were derived from the genetically isolated Finnish population, the critical region for RS could be narrowed to 0.2-0.3 cM, between the markers DXS418 and HYAT1.

SUBMITTER: Huopaniemi L

PROVIDER: S-EPMC1712451 | biostudies-other | 1997 May

REPOSITORIES: biostudies-other

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Publications

Linkage disequilibrium and physical mapping of X-linked juvenile retinoschisis.

Huopaniemi L L Rantala A A Tahvanainen E E de la Chapelle A A Alitalo T T

American journal of human genetics 19970501 5

X-linked juvenile retinoschisis (RS) is a recessively inherited disorder resulting in poor visual acuity. Affected males typically show retinal degeneration and intraretinal splitting. The prevalence of RS is 1:15,000-1:30,000. Elsewhere we have mapped the RS gene between the markers DXS43 and DXS274 in Xp22.1-p22.2. To narrow the RS region, we analyzed 31 Finnish RS families with the markers DXS418, DXS999, DXS7161, and DXS365 and a new polymorphic microsatellite marker, HYAT1. Multipoint linka ...[more]

PMID: 9150161

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Project description:Mapping by admixture linkage disequilibrium (MALD) is a potentially powerful technique for the mapping of complex genetic diseases. The practical requirements of this method include (a) a set of markers spanning the genome that have large allele-frequency differences between the parental ethnicities contributing to the admixed population and (b) an understanding of the extent of admixture in the study population. To this end, a DNA-pooling technique was used to screen microsatellite and diallelic insertion/deletion markers for allele-frequency differences between putative representatives of the parental populations of the admixed Mexican American (MA) and African American (AA) populations. Markers with promising pooled differences were then confirmed by individual genotyping in both the parental and admixed populations. For the MA population, screening of >600 markers identified 151 ethnic-difference markers (EDMs) with delta>0.30 (where delta is the absolute value of each allele-frequency difference between two populations, summed over all marker alleles and divided by two) that are likely to be useful for MALD analysis. For the AA population, analysis of >400 markers identified 97 EDMs. In addition, individual genotyping of these markers in Pima Amerindians, Yavapai Amerindians, European American (EA) individuals, Africans from Zimbabwe, MA individuals, and AA individuals, as well as comparison to the CEPH genotyping set, suggests that the differences between subpopulations of an ethnicity are small for many markers with large interethnic differences. Estimates of admixture that are based on individual genotyping of these markers are consistent with a 60% EA:40% Amerindian contribution to MA populations and with a 20% EA:80% African contribution to AA populations. Taken together, these data suggest that EDMs with large interpopulation and small intrapopulation differences can be readily identified for MALD studies in both AA and MA populations.

Dataset Information

Linkage disequilibrium and physical mapping of X-linked juvenile retinoschisis.

Publications

Linkage disequilibrium and physical mapping of X-linked juvenile retinoschisis.

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