The substitution of guanine (G) for adenine (A) at positioln 3243 of mitochondrial DNA, first demonstrated in MELAS patients, has been found in some diabetics, and this mutation seems to be one of genetic factors for diabetes mellitus. Because mutational mitochondria coexist with normal mitochondria (heteroplasmy), conventional PCR-RFLPm methods may not detect a mutation When a majority of the mitochondrial DNA in leukocytes is normal. We tested the efficacy of specific PCR amplification in detecting the 3243G mutation using a primer whonse 3' base was complementary to the mutational base. This mutation-specific PCR amplification method permitted detection of the mutation in 2 patients with MELAS and in a diabetic patient whose mutation was detected by the PCR-RFLP method in biopsied muscle but not in peripheral leukocytes, and in two other diabetic patients.Specific PCR amplification for detection of the 3243G mutation is a simple and senisitive method and is useful inevaluating this mutation in diabetes mellituls.
