Respiratory chain complex III deficiency due to mutated BCS1L : a novel phenotype with encephalomyopathy, partially phenocopied in a Bcs1l mutant mouse model

Background Mitochondrial diseasesdue to defective respiratory chain complexIII (CIII) are relatively uncommon. The assembly of the eleven-subunit CIII is completed by the insertion of the Rieske iron-sulfur protein, a process for which BCS1Lprotein is indispensable. Mutations in the BCS1Lgene constitute the most common diagnosed cause of CIII deficiency, and the phenotypic spectrum arising from mutations in this gene is wide.