• cataract
• lens
• genetic
• crystallin
• paediatrics

Congenital cataract, although uncommon, accounts for about 10% of childhood blindness.¹ The cataract is usually seen as an isolated abnormality but may occur in association with other ocular developmental or systemic abnormalities. About 50% of bilateral cases have a genetic basis. Congenital cataract is both clinically and genetically heterogeneous; isolated congenital cataract is usually inherited as an autosomal dominant trait although autosomal recessive and X linked inheritance are seen less commonly.² Most progress has been made in identifying the genes causing autosomal dominant congenital cataract.² Two main approaches have been used to identify the causative mutations. In large families linkage analysis has been used to identify the chromosomal locus followed by screening of positional candidate genes; most genes have been identified using this strategy. A second approach has been to screen DNA from large panels of patients with inherited cataract for mutation in the many candidate genes available.

The α, β, and γ-crystallins are stable water soluble proteins which are highly expressed in the lens; they account for about 90% of total lens protein, have a key role in lens transparency, and thus represent excellent candidate genes for inherited cataract.³ α-Crystallin is made up of two polypeptides αA and αB encoded by the CRYAA gene on chromosome 21q22.3 and CRYAB gene on 11q22–q22.3, respectively. In addition to its …