Definition of Maturity onset diabetes of the young

Maturity onset diabetes of the young: Diabetes mellitus that has early onset (usually before the age of 25), is non-insulin-dependent, and is inherited in an autosomal dominant manner. Abbreviated MODY.

MODY is often considered a subtype of type 2 diabetes but it is unlike the usual type 2 diabetes in that insulin secretion, not the action of insulin, is impaired. There is no problem with insulin sensitivity.

MODY accounts for 2-5% of all non-insulin-dependent diabetes. There are a number of forms of MODY which are called MODY1, MODY2, and so on:

• MODY1 is caused by mutation in the hepatocyte nuclear factor-4-alpha gene (HNF4A) on chromosome 20.
• MODY2 is caused by mutation in the glucokinase gene (GCK) on chromosome 7.
• MODY3 is caused by mutation in the hepatic transcription factor-1 gene (TCF1) on chromosome 12q24.2.
• MODY4 is caused by mutation in the insulin promoter factor-1 gene (IPF1) on chromosome 13q12.1.
• MODY5 is caused by mutation in the gene encoding hepatic transcription factor-2 (TCF2) on chromosome 17cen-q21.3.
• MODY6 is caused by mutation in the gene encoding neurogenic differentiation 1 (NEUROD1) on chromosome 2q32.

Note that genes for MODY are on at least 6 different chromosomes. But two forms, MODY1 and MODY3, are due to mutations in genes that encode hepatocyte nuclear factors (HNF) -- transcription factors that govern the expression of other genes.