Gene mapping in a highly inbred consanguineous foveal hypoplasia family to cytogenetic region 16q24.1

A highly inbred uncle-niece, second degree consanguineous Foveal hypoplasia affected family with four members was subjected to gene mapping. Members underwent detailed ophthalmic evaluation including best corrected distance and near vision measurements, color vision assessment, fundus evaluation and flourescence angiography, horizontal corneal diameter measurement, total axial length measurement, optical coherence tomography and full-field electroretinogram. Peripheral blood was drawn from the members and DNA was extracted using Macherey-Nagel maxi kit (Germany). Gene mapping was performed by the Affymetrix SNP 6.0 Genechip through homozygosity mapping technique. Two point, multipoint analyses and haplotyping for all the 400 odd markers on chromosome 16 were performed. LOD score of 2.3 was obtained for the marker rs254347 and the disease segregated with the haplotypes. No other region showed similar significant association. The gene for foveal hypoplasia may be located on chromosome 16, near the SNP marker rs254347 at cytogenetic region 16q24.1.   Key words: Haplotyping, homozygosity mapping, chromosomes, consanguinity.