COQ4 and multiple system atrophy: Other proteins involved in the biosynthesis of CoQ10 were found in elevated concentrations in MSA, including decaprenyl diphosphate synthase subunit 2 (PDSS2), 4-hydroxy-3-methoxy-5-polyprenylbenzoate decarboxylase (COQ4) and aarF domain-containing kinase 3 (COQ8A) [13].