NMNAT1 and musculoskeletal system disorder: Considering the involvement of a particular gene in various diseases, Col4a1 (linking nervous, musculoskeletal and urinary system diseases and physical disorders), Ctnna2 (linking immune, endocrine, and metabolic diseases), and Nmnat1 (linking nervous and musculoskeletal diseases and physical disorders) might be core genes containing PAS-SNPs in the Fat line (Fig. 4A).