To observe patterns of somatic mosaicism of FMR1 in our long-read sequencing, we proceeded with one female and one male FXTAS case, FXPM5006 and FXPM1008–20-RF, both of which demonstrated the highest ii out of their respective cohorts (Supplemental Figure 1s,t, Supplemental Table 2). This evidence concerns the gene FMR1 and fragile X-associated tremor/ataxia syndrome.