THE 3243-MELAS MUTATION IN A PEDIGREE WITH MERRF

A mutation at base pair (bp) 3243 in mitochondrial DNA has been associ ated with mitochondrial myopathy, encephalomyopathy, lactic acidosis a nd stroke-like episodes (MELAS). A mutation at bp 8344 has been descri bed as the cause of myoclonic epilepsy and ragged-red fiber disease (M ERRF). Mitochondrial DNA was analyzed in a family with symptoms and si gns consistent with MERRF. The DNA regions flanking bp 3243 and bp 834 4 were amplified using the polymerase chain reaction, and the products were digested with restriction enzymes. The MELAS mutation at bp 3243 was found, but not the mutation at bp 8344. This illustrates the dive rse clinical manifestations of the MELAS mutation.