PMPCA and mitochondrial disease: In addition, a c.1066G>A (p.Gly356Ser) mutation in the glycine-rich loop (residues 345-358) of PMPCA together with the c.1129G>A (p.Ala377Thr) mutation, located 20 residues downstream of the loop, leads to a severe mitochondrial disease manifested by muscle weakness, extensive brain atrophy, visual impairment, and respiratory defects [48] (Table 1).