LAUSR

Succinate dehydrogenase (SDH), or respiratory complex II, consists of four nuclear-encoded subunits. The chaperone protein succinate dehydrogenase assembly factor 1 (SDHAF1) plays an essential role in the assembly of SDH, and in the incorporation of iron-sulfur clusters into the SDHB subunit. SDHB couples the oxidation of succinate to fumarate with the reduction of ubiquinone (coenzyme Q) to ubiquinol. Previously reported mutations in SDHAF1 have been associated with infantile leukoencephalopathy. We report an adult case with a homozygous variant of uncertain significance (VUS) mutation in SDHAF1, presenting with dementia, spastic paraparesis, and cardiomyopathy, initially diagnosed as multiple sclerosis.