MATERNALLY TRANSMITTED PARTIAL DIRECT TANDEM DUPLICATION OF MITOCHONDRIAL-DNA ASSOCIATED WITH DIABETES-MELLITUS

Mitochondrial DNA from a 38 year old male with diabetes mellitus and f eatures of mitochondrial dysfunction was analysed and shown to include a population with a partial duplication. The partially duplicated mit ochondrial DNA molecules were evident in both muscle and blood. The re gion of mitochondrial DNA duplicated includes the origin of heavy stra nd replication, but not the light strand origin. This patient has feat ures in common with other cases of partial direct tandem duplications and with a family which was reported to harbour a 10.4 kb mtDNA deleti on. Initial restriction enzyme analysis of our case produced results c onsistent with a partial deletion of mitochondrial DNA. This leads us to propose that the rarity of reports of partial mitochondrial DNA dup lications may stem in part from the classification of such mutants as partial deletions.