Among these TP53 + / + biopsies, we observed no significant differences in mutation load (P = 0.507), SCA (P = 0.18), or SV count (P = 0.692) between CO and NCO; thus most CO patients have some BE biopsies that are indistinguishable from NCO biopsies. The gene discussed is TP53; the disease is autosomal dominant cerebellar ataxia.