Also known as Glycogen Storage Disease Type V (GSD V), Phosphorylase Deficiency, and Myophosphorylase Deficiency.
McArdle’s disease is an inherited condition that affects the skeletal muscles, causing severe muscle pain and cramping. It is caused by the lack of an enzyme called phosphorylase or myophosphorylase, which is needed to break down glycogen (stored form of sugar). Without the enzyme, glycogen can’t be used to produce energy during exercise.
McArdle’s disease is rare, and its prevalence is unknown. The condition is present from birth, but may not be diagnosed until young adulthood. People with McArdle’s disease often report they had symptoms, such as painful muscle spasms, during childhood. Treatment may include physiotherapy and regular moderate exercise (i.e. walking).
Important: Some anaesthetics used during surgery can cause acute muscle damage or other complications. You should notify the surgeon and/or the anesthesiologist that you have been diagnosed with McArdle’s disease prior to receiving any anaesthetics.