This includes PYGM-deficiency (McArdle disease) [43]; lack of AMPD1, which causes metabolic myopathy in humans [44]; and loss-of-function mutations in the CAPN3 gene that have been associated with limb-girdle muscular dystrophy type 2A (LGMD2A) [27]. Here, PYGM is linked to autosomal recessive limb-girdle muscular dystrophy type 2A.