Maturity-onset diabetes of the young type 2

MODY is a form of NIDDM (125853) characterized by monogenic autosomal dominant transmission and early age of onset. For a general phenotypic description and a discussion of genetic heterogeneity of MODY, see 606391. In a review of the various forms of MODY, Fajans et al. (2001) stated that glucokinase-related MODY2 is a common form of the disorder, especially in children with mild hyperglycemia and in women with gestational diabetes and a family history of diabetes. It has been described in persons of all racial and ethnic groups. More than 130 MODY-associated mutations have been found in the glucokinase gene. Heterozygous mutations in glucokinase are associated with a mild form of nonprogressive hyperglycemia that is usually asymptomatic at diagnosis and is treated with diet alone. The mild fasting hyperglycemia with blood glucose concentrations of 110 to 145 mg/deciliter and impaired glucose tolerance in most affected carriers may be recognized by biochemical testing at a young age, possibly as early as birth. About 50% of the women who are carriers may have gestational diabetes. Less than 50% of the carriers have overt diabetes; many of those who do are obese or elderly. Two percent of MODY2 patients require insulin therapy. Diabetes-associated complications are rare in this form of MODY. MODY was found in 13% of the Caucasian NIDDM families collected in France by Froguel et al. (1991). Gidh-Jain et al. (1993) found that GCK mutations accounted for 56% of MODY families in France. [from OMIM]