Here, we report the case of a patient with an RYR1 pathogenic variant associated with MH and cores who developed an alveolar rhabdomyosarcoma associated with a germline variant in the cancer predisposition gene ASPSCR1 (Alveolar Soft Part Sarcoma Chromosomal Region Candidate 1). This evidence concerns the gene RYR1 and alveolar rhabdomyosarcoma.