Although such treatments do not affect cell proliferation at the experimental tested condition, it induces a decrease in MRFs, desmin, irisin, myostatin, MHC, FGFRs, and α-KLOTHO gene expression during differentiation, indicating the possible involvement of FGF23 in muscular dysfunction characterizing hypophosphatemic rickets and the possible presence of negative feedback providing protection against high FGF23 levels. Here, FNDC5 is linked to hypophosphatemic rickets.