MITOCHONDRIAL TRNA(CYS) GENE MUTATION (A5814G) - A 2ND FAMILY WITH MITOCHONDRIAL ENCEPHALOPATHY

We report an Italian family with maternally inherited encephalomyopath y including progressive external ophthalmoplegia, seizures, and neurop hysiological evidence of brainstem dysfunction. Mitochondrial DNA anal ysis showed a heteroplasmic point mutation at position 5814 in the tRN A gene for cysteine (A5814G), previously reported in a 5-year-old girl of Portuguese origin. The mutation was very abundant (>95%) in both m uscle and blood from the proposita and was present in lower proportion s (average 85 +/- 6%) in blood from three less severely affected mater nal relatives. This observation confirms pathogenicity for the A5814G mutation. (C) 1997 Elsevier Science B.V.