MATERNALLY-INHERITED DIABETES AND DEAFNESS - REPORT OF 2 AFFECTED GERMAN FAMILIES WITH THE A3243G MITOCHONDRIAL-DNA MUTATION

In two German families four patients containing the A3243G mutant in t he mitochondrial DNA suffered from maternally-inherited diabetes and d eafness (MIDD). DNA was isolated from oral mucosa cells. Using the pol ymerase chain reaction with not vet published primers, we obtained aft er digestion with the restriction endonuclease BSP 120I two oligonucle otides of comparable size increasing the sensitivity of our method two times. Under these conditions we were able to detect 0.8% of the muta ted DNA. In general, the patients show the characteristics proposed fo r MIDD by Maassen et al. (1997), however, there are some differences: age at onset (in our study 36-45 y), body mass index (>26 kg/m(2)). In addition, our study shows that MIDD may be combined with neuronal dis orders (M. Parkinson, epilepsy) and/or endocrinopathies (M. Addison). Our data indicate that MIDD is a heterogeneous disease. On the other h and, in one family there are healthy probands with a high concentratio n of mutated mitochondrial DNA.