CDK6 and autosomal dominant cerebellar ataxia: The WBC and the related absolute neutrophil count (ANC) were selected as important biomarkers because of their documented importance in overall clinical severity and mortality of SCA,[2–4] and their recognized influence on the hydroxyurea maximal tolerated dose (MTD).[14,15] Genetic variants known to affect the WBC count, including polymorphisms in DARC, PSMD3-CSF, CXCL2, and CDK6 genes[16–18] have not been carefully investigated in children with SCA.