The five mutations hitherto reported in SCO2 are known to cause COX deficiency with fatal infantile cardioencephalomyopathy (CEMCOX1) [2,3], myopia (MYP6) [4], Leigh syndrome [5] or early-onset axonal Charcot-Marie-Tooth disease [6]. This evidence concerns the gene SCO2 and mitochondrial complex IV deficiency, nuclear-type.