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Autosomal recessive retinitis pigmentosa locus maps on chromosome 1q in a large consanguineous family from Pakistan
Author(s) -
Leutelt Jutta,
Oehlmann Ralph,
Younus Farah,
Born L. Ingeborgh,
Weber James L.,
Denton Michael J.,
Mehdi S. Qasim,
Gal Andreas
Publication year - 1995
Publication title -
clinical genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 102
eISSN - 1399-0004
pISSN - 0009-9163
DOI - 10.1111/j.1399-0004.1995.tb03943.x
Subject(s) - retinitis pigmentosa , locus (genetics) , genetics , consanguinity , locus heterogeneity , biology , consanguineous marriage , medicine , genetic heterogeneity , gene , phenotype
A large Pakistani family with several consanguineous marriages is described, in which autosomal recessive retinitis pigmentosa is segregating. Linkage studies revealed close linkage between the disease locus and six loci on chromosome 1q (D1S158, F13B, D1S422, D1S412, D1S413, and D1S53) with maximum lod scores ranging from 0.988‐4.657 at Θ=0.065‐0.235. However, the analysis of individual nuclear families showed very close linkage without recombination in three branches and several recombinants and negative lod scores throughout in the fourth branch. These results strongly suggest that mutations of two different genes are responsible for the disease in the ‘linked’ and ‘unlinked’ branches. Parallel to the linkage heterogeneity, clear phenotypic differences have been observed among the ‘linked’ and ‘unlinked’ parts. Our findings demonstrate that in case of recessive disorders the possibility of non‐allelic genetic heterogeneity should always be considered, even within the same kindred and in genetic isolates if a largely extended pedigree is analysed.