MITOCHONDRIAL MYOPATHY ASSOCIATED WITH SUDDEN-DEATH IN YOUNG-ADULTS AND A NOVEL MUTATION IN THE MITOCHONDRIAL-DNA LEUCINE TRANSFER RNA(UUR)GENE

A family exhibited maternal inheritance of a variable syndrome compris ing ocular, neck and proximal upper limb weakness, psychiatric feature s, and sudden death. Of 15 definitely or probably affected individuals , 7 had died in early adult life, probably of respiratory failure. A n ovel point mutation of mitochondrial DNA, in a transfer RNA gene at po sition 3251, was detected in all living affected family members.