Autosomal dominant 'zonular pulverulent' cataract linked to human chromosome

Purpose. Inherited cataract is a clinically and genetically heterogeneous lens disease that most often presents as a congenital autosomal dominant trait. To gain further insight into the etiology of inherited cataract we have used molecular genetic linkage analysis to map the gene for autosomal dominant 'zonular pulverulent' cataract in a five-generation English pedigree. Methods. Genomic DNA was extracted from blood samples, taken with informed consent, from 27 family members. For genotyping, Généthon microsatellite markers were amplified using the polymerase chain reaction and 5'-end 32P-labeled primers, then separated on sequencing gels and detected by autoradiography. Genetic linkage analysis was performed using the LINKAGE package of programs. Results. After exclusion of eight known loci and several candidate lens genes for autosomal dominant cataract, we obtained significantly positive LOD scores for markers D13S1236 (Z = 5.75, 8 = 0) and D13S175 (Z = 4.06, 0 = 0). Multipoint analysis gave a maximum LOD score of 6.62 (0 = 0) at DI3S175 and haplotype analysis indicated that the cataract gene probably lies in the centromeric region of chromosome 13q. Conclusions. This study maps a new locus for inherited 'zonular pulverulent1 cataract on chromosome 13 and brings the current number of loci for autosomal dominant cataract to at least nine. The gene for lens connexin 46 has also been mapped to the same region of chromosome 13 and represents an attractive candidate eene for 'zonular pulverulent' cataract in this family.