Although limited is known on the identity and specific function of these FAP subtypes, based on a recent study on FAP involvement in FSHD it is tempting to speculate that both subtypes may represent different pathological states, either facilitating muscle regeneration (in early stages of disease, DUX4 signature-associated) or muscle fibrosis, fat accumulation and atrophy (in late stage of disease, PAX7 score-associated)49. The gene discussed is DUX4; the disease is facioscapulohumeral muscular dystrophy.