A NEW MTDNA MUTATION IN THE TRNA(LEU(UUR)) GENE ASSOCIATED WITH MATERNALLY INHERITED CARDIOMYOPATHY

We report a new mutation, a C to T transition at nt 3303 of mtDNA, in seven members of a family with cardiomyopathy and myopathy: the proban d and two siblings had fatal infantile cardiomyopathy, whereas in thre e maternal relatives the disease manifested later in life as sudden ca rdiac death or as mitochondrial myopathy with cardiomyopathy. The muta tion was homoplasmic in all tissues (including blood) from the proband and her brother, but heteroplasmic in brood from five oligosymptomati c or asymptomatic maternal relatives. This mutation disrupts a conserv ed base pair in the aminoacyl stem of the tRNA(Leu(UUR)). None of 70 c ontrols carried the mutation, Our data indicate that this mutation is the genetic cause of the disorder in this family, and confirm that the tRNA(Leu(UUR)) is a ''hot spot'' for mutations in mtDNA. (C) 1994 Wil ey-Liss, Inc.