Diabetes mellitus and deafness

Diabetes mellitus and deafness (DAD) or maternally inherited diabetes and deafness (MIDD) is a subtype of diabetes which is caused from a point mutation at position 3243 in human mitochondrial DNA, which consists of a circular genome. This affects the gene encoding tRNALeu. Because mitochondrial DNA is contributed to the embryo by the oocyte and not by spermatozoa, this disease is inherited from maternal family members only. As indicated by the name, MIDD is characterized by diabetes and sensorineural hearing loss.