ClinVar

Mariotti et al. (1994) studied a 23-year-old man, subject III-1 in the report by Zeviani et al. (1991), who suffered from heart failure and muscle weakness due to skeletal myopathy with ragged-red fibers. He had signs of congestive heart failure. Densitometric quantitation showed that 90% of mtDNA extracted from skeletal muscle was mutant. A point mutation in the MTTL1 gene was shown to be an A-to-G transition at nucleotide position 3260. The disorder was of adult onset and inherited from the mother. From study of respiratory capacity and mitochondrial protein synthesis in transformant cybrids harboring the mutation, Mariotti et al. (1994) proved that the G3260 mutation was responsible for the clinical disorder in this family. They recommended the transformant cybrid system for evaluating the pathogenic potential of mtDNA mutations.