Tags: Disease.
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. Due to the fact that mitochondrial DNA is only found in oocytes and is not present in spermatozoa this disease is inherited from maternal family members only.