A new locus in chromosome 2q37-qter is associated with posterior polar cataract

Abstract

To study the genetic basis of autosomal dominant posterior polar cataracts in two Chinese pedigrees. Peripheral blood samples were collected and genomic DNA was isolated. A genome-wide scan, using microsatellite markers at approximately 10-cm intervals and additional microsatellite markers for the positive region, was performed. Haplotype data were processed using Cyrillic software (version 2.1) to define the region of the disease gene. Mutation analysis was carried out for candidate genes. Sequencing data were analyzed with the software Sequence Scanner v1.0. A maximum two-point LOD score (Z (max)) of 2.53 and 2.03 was obtained at marker D2S125 with recombination θ = 0.00 in the two families. The possible disease genes were located at approximately 8.44-cM between the marker D2S125 and the terminal of chromosome 2q, namely, 2q37-qter. Candidate genes, such as Gamma-crystallins (CRYGA-D), septin 2 (SEPT2), aquaporin 12B (AQP12B), and chemokine orphan receptor 7 (CXCR7), were sequenced but no causative mutations were found. Our results suggest that an unidentified gene in chromosome 2q37-qter is associated with posterior polar cataract, which may have an implication in understanding the genetic and molecular mechanisms of cataracts.