Maturity-onset Diabetes of the Young: from Clinical Description to Molecular Genetic Characterization

Maturity-onset diabetes of the young is a heterogeneous group of autosomal dominantly inherited, young-onset beta-cell disorders. At least two consecutive generations are affected with a family member diagnosed before 25 years of age. Diabetes is caused either by mutations in the glucokinase gene (glucokinase MODY) or by mutations in transcription factors (transcription factor MODY). Glucokinase maturity-onset diabetes of the young is a mild, non-progressive hyperglycaemia caused by a resetting of the pancreatic glucose sensor. It is treated with diet, and complications are rare. Pregnancies affected by glucokinase mutations have specific management strategies and prognosis. Transcription factor maturity-onset diabetes of the young, caused by mutations in the hepatocyte nuclear factor genes HNF-1alpha, HNF-4alpha and HNF-1beta, and in insulin promoter factor-1 results in a progressive beta-cell defect with increasing treatment requirements and diabetic complications. Cystic renal disease is a prominent feature of HNF-1beta mutations. Further maturity-onset diabetes of the young genes remain to be identified. MODY is part of the differential diagnosis of diabetes presenting in the first to third decades of life. Diagnostic molecular genetic testing is available for the more common genes involved.