In this study, we have identified an identical 964 kb haplotype found in linkage disequilibrium flanking the (ATTTC)n repeat inserted mutation (chr1:56785142–57749488, hg38) shared by all SCA37 patients studied from 14 Spanish and Portuguese kindreds, indicating that an ancestral chromosome is responsible for all SCA37 cases in the Iberian Peninsula described to date. Here, LGR5 is linked to spinocerebellar ataxia type 37.