In backfat thickness traits, the most significant SNP was located at 12,758,893 bp on SSC7 with 38,175 bp upstream of the ATXN1 gene, which was significantly associated with MBD, with a P-value of 4.05 × 10−8 (Table 3). The gene discussed is ATXN1; the disease is Marchiafava-Bignami disease.