MODY4 is caused by mutations in the insulin promoter factor-1 (IPF1; OMIM 600733) gene on chromosome 13q12.1.  IPF1 is a pancreatic transcription factor that regulates expression of insulin, somatostatin and other genes. In addition, IPF1 is involved in the development of the pancreas. In adults, the expression of IPF1 is restricted to cells of the pancreas. Individuals with MODY4 mutations have decreased binding activity to the insulin gene promoter, which leads to reduced activation of the insulin gene in response to glucose.

 

MODY4 mutations have also been associated with T2D. At least 6 genetic variants have been identified, including frameshift, insertions and missense mutations.  They contribute to ~1% of all MODY cases.