The prevalence of biallelic RFC1 pathogenic expansions has been shown to vary significantly between different late-onset ataxia cohorts, ranging from 1.1% in a Canadian-Brazilian study6 to 28.9% in a British cohort study13 (3.2% in a North American cohort,30 6.5% within a Greek cohort,31 5.2–10.8% within Japanese cohorts,8,10 14% in a Turkish cohort,32 14.5% within an Italian cohort,33 15% in a French cohort34 and 20.2% within a German cohort35). The gene discussed is RFC1; the disease is cerebellar ataxia.