PYGM and muscular disease: Histochemical examination of a muscle biopsy revealed the absence of myophosphorylase activity, while gene analysis identified a known early-onset McArdle mutation in the PYGM gene.<h4>Conclusion</h4>This case highlights that the clinical spectrum of PYGM gene mutation typically manifest during adolescence, but it is also a differential diagnosis in late onset muscle disorders and emphases the investigation of the role of ACE inhibitors in this disease.