Homozygous Insulin Promotor Gene Mutation Causing Permanent Neonatal Diabetes Mellitus and Childhood Onset Autoantibody Negative Diabetes in the Same Family.

Homozygous INS gene promotor mutations may present with either PNDM or later onset autoantibody negative diabetes in childhood. This suggests that homozygous INS gene promotor mutations show marked heterogeneity in clinical presentation within individuals in the same family. The pathophysiology of this is not well known but could be related to a number of factors, including the position of the variant, penetrance, other associated genetic defects, HLA etc. Premarital screening and genetic counselling is recommended for highly consanguineous families to reduce occurrence of such conditions.