An autosomal dominant cataract locus mapped to 19q13-qter in a Chinese family

PURPOSE: The aim of this study was to map the disease locus of autosomal dominant cataracts (ADC) in a Chinese family. METHODS: A four-generation family with multiple individuals affected by ADC was investigated. Genomic DNA was collected from 22 family members. A gene-scan at known candidate ADC loci was performed. To achieve fine-mapping we genotyped fourteen STR markers at the critical region of 19q. The two-point logarithm of odds (LOD) score was calculated using Linkage Software Package Version 5.1 for linkage analysis. The haplotype was constructed using Cyrillic software. RESULTS: Ten members of this Chinese family were affected by nuclear cataracts. Initially, linkage analysis revealed a significant LOD score of 3.82 at the STR marker D19S418. Subsequently, after refine-marker analysis, a maximum LOD score (Z(max)=4.25) was obtained at the D19S877 (θ=0). Haplotype analysis also confirmed the locus and further narrowed it down to a critical interval from the marker D19S924 to the 19qter. CONCLUSIONS: We have successfully mapped an ADC locus to 19q13-qter. Previous studies have identified three cataract loci on 19q; however, we found no overlap between the locus of this study and any of the previously identified loci. We therefore suggest that the 19q13-qter locus in this family is a new locus for ADC.