Congenital cataract is the leading cause of reversible blindness in childhood, with prevalence of one to five cases per 10.000 live births. The hereditary form corresponds to about 50% of these cases. The autosomal dominant inheritance is the most frequent, but is also observed autosomal recessive and X-linked. The genetic alterations responsible for non-syndromic congenital cataracts lead to changes in lens proteins: crystallins, connexins, MIPs (Major Intrinsic Proteins) and BFSP2 (Beaded Filament Structural Protein 2) of the cytoskeletal. Mutations in the nucleotide sequence of the iron responsive element (IRE) of the gene Lightferritin (LFT) and alterations in genes related with ocular development: HSF4 (Heat Shock Transcription Factor 4), PITX3 (Paired-like Homeodomain Transcription Factor 3) and MAF (Avian Musculoaponeurotic Fibrosarcoma) are also associated with the disease. Nuclear and lamellar cataracts are two of the most common forms of congenital opacities, and alterations in the CX46 and CX50 genes, that encode connexin proteins, have been related to the nuclear phenotype, while alterations in the HSF4 gene have been associated with the lamellar phenotype. The present study aims, through direct sequencing, to determine structural alterations in the CX46, CX50 and HSF4 genes in patients with nuclear and lamellar bilateral congenital cataracts with hereditary etiology and compare with literature data, enabling better understanding of hereditary congenital cataracts and of the relationship with the observed structural alterations.
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