COQ8A and autosomal recessive ataxia due to ubiquinone deficiency: Primary coenzyme Q10 deficiency-4 (also known as COQ8A-ataxia, autosomal recessive cerebellar ataxia 2 (ARCA2), or autosomal recessive spinocerebellar ataxia-9 (SCAR9)) is a mitochondrial disorder caused by the mutation in the COQ8A gene (previously: ADCK3, CABC1) and characterized by a reduced level of coenzyme Q10 (CoQ10, ubiquinone) [3].