NOVEL NDUFS 4 GENE MUTATION IN AN ATYPICAL LATE-ONSET MITOCHONDRIAL FORM OF MULTIFOCAL DYSTONIA Mitochondrial

Mitochondrial complex I, the largest component of the mitochondrial respiratory chain, comprises 44 subunits of which 7 are encoded by the mitochondrial genome and the remainder by the nuclear genome. Isolated complex I deficiencies represent a major contribution within the group of respiratory chain defects. We report an atypical case carrying a homozygous NDUFS4 missense mutation, with late-onset multifocal dystonia, in contrast to expected clinical phenotypes due to otherNDUFS4mutations, which have been constantly reported to be responsible for Leigh syndrome of early onset and death.