Dense cataract and microphthalmia--new spontaneous mutation in BALB/c mice.

We describe a new spontaneous mutation in BALB/c mice that causes abnormal phenotype, such as congenital cataract and microphthalmia. This abnormality was found to be inheritable because offspring with the same abnormality were produced by backcrossing the abnormal male to its normal female parent. Results of various crosses made to determine the mode of inheritance indicated that this abnormality is attributable to mutation of an autosomal recessive gene. Slit lamp examination of the mutant eyes revealed total lenticular opacity, disturbed typical iris pattern, and abnormal pupillary muscle development. Histologic changes in mutant eyes between gestation day 13 and postnatal day 1 indicated various eye and lens abnormalities, including microphthalmia; underdeveloped iris, optic stalk, cornea, and retina; degenerated lens fibers with lost fibrillar structure; and vacuoles of various sizes at the posterior border of the lens. Mild opacity of the lens was found to progress with age and became denser, resembling mature cataract, and occupying the lens completely at the age of six to eight weeks. We, therefore, temporarily designated this abnormality as dense cataract and microphthalmia, with the gene symbol dcm.