Abstract
Abstract: :
Purpose: Congenital cataracts are a leading cause of visual disability in children. Approximately 50% of this type of cataracts are hereditary, most frequently transmitted as an autosomal dominant trait. Congenital acueliform cataract is one of the rarest types of inherited cataract and is characterized by fiberglass–like or needle–like crystals projecting in different directions, through or close to the axial region of the lens. The opacity is usually bilateral and is associated with a variable degree of visual loss. Previously, crystallin Gamma D gene (CRYGD) mutations were demonstrated in 3 families (two from Switzerland and the other one from Macedonia) with aculeiform cataract; interestingly, the same Arg–58 to Hys mutation was identified in these three unrelated pedigrees. Here, we report the results of CRYGD molecular analyses in a large Mexican family with autosomal dominant aculeiform cataract. Methods: The propositus is a female aged 23 years who asked for medical advice at the Institute of Ophthalmology "Conde de Valenciana" in Mexico City because of "low visual acuity" from childhood; familial history disclosed that several relatives were previously diagnosed as having bilateral congenital cataracts; on examination, her visual acuity was 20/200 in both eyes while a best corrected VA of 20/25 in the right eye and 20/30 in the left eye was recorded. On biomicroscopy, a white central opacity resembling glass, originating from the fetal nucleus and radially projecting needle–like crystals, was observed in both lenses. Fourteen relatives were clinically examined and 7 of them were identified as suffering from the same type of bilateral cataract. Results: Molecular analyses on genomic DNA from the propositus and from 5 affected relatives demonstrated a G to A heterozygous missense mutation in position 411 in exon 2 of CRYGD, which originates a Arg–58 to Hys substitution in the protein. Conclusions: The Arg–58 to Hys substitution identified in this family is identical to that previously demonstrated in three unrelated familes with aculeiform cataract. The available molecular data suggests that there is a strict genotype–phenotype correlation in this type of congenital hereditary cataract.
Keywords: cataract • genetics • mutations