Autosomal recessive missense mutations in LRPPRC cause the French-Canadian Type of Leigh Syndrome (LSFC), a rare mitochondrial disease-causing cytochrome c oxidase (COX, complex IV (CIV)) deficiency, which results in severe neurological, muscular, and kidney pathology, lactic acidosis, and premature death [81–83]. The gene discussed is LRPPRC; the disease is congenital lactic acidosis, Saguenay-Lac-Saint-Jean type.