PYGM and glycogen storage disease V: Remarkably, whereas myophosphorylase expression was increased in Complex I deficient biopsies (Table 1 and Additional file 4: Figure S4) it was completely vanished in patients affected of Glycogenosis type V (Table 1 and Additional file 4: Figure S4), consistent with the lack of myophosphorylase activity in McArdle disease [16,17].