Molecular genetics of cataracts

Genetic causes of cataracts are well recognized. For example, if the keyword “cataract” is used to search McKusick’s Online Mendelian Inheritance in Man over 280 entries are retrieved, many of which include animal, mostly mouse, models of human cataracts (70). Although genetic types of cataracts can present at any age, most are congenital, infantile or childhood, and may be divided into two broad categories based on their association with other phenotypes. Nonsyndromic cataracts present as an isolated lens defect in the absence of systemic and/or other ocular phenotypes. In certain cases, however, microcornea may accompany these cataracts in part reflecting the “organizer” role of the lens in anterior eye development (7). In contrast, syndromic cataracts present as a secondary, often inconsistent, feature of over 100 genetically diverse disorders involving systemic and/or other ocular phenotypes.