| Abstract: | Maturity‐onset diabetes of the young (MODY) is a monogenic subgroup of non‐insulin dependent diabetes (NIDDM) characterized by an early age of diagnosis (usually < 25 years) and an autosomal dominant mode of inheritance. Mutations in the hepatocyte nuclear factor 1 alpha (HNF‐1α) [MODY3] gene represent the most common cause of MODY in the UK and a common cause of MODY in many other populations. Sixty‐three different mutations have been described in a total of 112 families worldwide. This report describes two families, not known to be related, who carry a novel insertion/deletion mutation (I414G415ATCG→CCA) and a 6bp intronic deletion of the HNF‐1α gene in cis. We propose that the insertion/deletion mutation has arisen by formation of a hairpin loop due to the presence of a quasi‐palindromic sequence, followed by insertion of CC and deletion of TCG resulting in the increased stability of the hairpin loop. Hum Mutat 16:273, 2000. © 2000 Wiley‐Liss, Inc. |
