PHKA2 and glycogen storage disease III: In other glycogen storage diseases, such as type III (GSDIII, Cori-Forbes disease) or VIII and IX, skeletal muscle damage is related to other specific deficit enzymes involved in glycogen breakdown, respectively amylo-alpha-1,6-glucosidase or 4-alpha-glucanotransferase (AGL) and liver phosphorylase b kinase (PhK) enzyme.