RFC1 and Friedreich ataxia: For autosomal recessive REDs, we found a carrier frequency (that is, people who carry one expanded allele) of 1 in 101 for FXN (FA) and 1 in 14 for RFC1, and a frequency of biallelic expansions of 1 in 82,176 for FXN (FA) and 1 in 712 for RFC1 CANVAS (Fig. 2 and Supplementary Table 8).