Characterization of congenital cataract and microphthalmia a new spontaneous mutant mouse model for hereditary eye diseases

Abstract

The present study deals with the characterization of dense cataract and microphthalmia (dcm), a congenital eye abnormality in the BALB/c mice. The eye abnormality, which was spontaneously noticed with congenital cataract and microphthalmia on 14th postnatal day when eyes are open, found to be inheritable in nature by backcrossing study. The colony of this mutant mouse was established by full sib mating. The affected mice exhibited mild opacity earlier, progressed with the age as a dense cataract, looked like mature cataract and occupied lens completely at the age of 8 weeks. The genetic experiments using standard breeding protocols revealed a genetic defect transmitted through autosomal recessive inheritance. Based on the appearance of mutant phenotype, the mutant mouse model was designated as dense cataract and microphthalmia (dcm). With the aim to study this eye abnormality in detail, dcm mouse model was extensively characterized for phenotypic, genetic, histological alterations, as well as identification of molecular lesion (s) and its relationship with the phenotype observed in the affected mice. The clinical examination of mutant phenotypes carried out by unaided eye and also with the help of ophthalmoscope at various ages, revealed four major eye defects such as bilateral cataract, microphthalmia, microphakia and aniridia. The mass measurements of mutant animals, eyes and lenses recorded at 0, 30, 60, 90 postnatal days and at 1 year age revealed that the body weights were not affected; however there was significant reduction in the weight and size of eyes and lenses. The decrease in eye and lens mass was noticed at all ages tested; irrespective of sex, revealing the significant impact of mutant gene(s) on postnatal growth of eyes and lenses except general body.