Abstract：Objective：The purpose of this study was to identify the disease causing gene in a family with autosomal dominant congenital posterior polar cataracts. Methods：The clinical data of the family were collected and the phenotypes of lens of affected family members were recorded by slit lamp photography. Genomic DNA was isolated from peripheral blood using TIANamp DNA Blood Mini Kits. Twenty-three mutational associated hot spots with autosomal dominant congenital posterior polar cataracts were screened by PCR-based DNA sequencing. The properties and structural models of wild type and mutant alpha B (αB)-crystallin (CRYAB) were generated and analyzed using ProtScale and ProtParam. Results：All the affected members in this family started to exhibit poor vision at the age of 8 to 10 years. The lens opacity consisted of a single, well-defined plaque with diameter of 0.5 to 3 mm, which was confined to the posterior pole of lens. DNA sequencing analysis of the affected members showed a novel, heterozygous missense mutation c.59C>G (P20R) in exon 1 of CRYAB gene. This mutation was not found in 10 unaffected members of the family and 200 unaffected and unrelated individuals, thereby excluding the possibility that it is a rare polymorphism. Data generated from ProtScale and ProtParam programs revealed that the mutation altered the biochemical properties of the αB-crystallin protein. Conclusion：This study reported a novel c.59C>G (P20R) missense mutation at CRYAB gene in a family with posterior polar cataract.