Glycogen Storage Disease, Type V (PYGM)

Glycogen storage disease, type V (GSD5) is an autosomal recessive muscle disease caused by pathogenic variants in the gene PYGM. The clinical presentation is variable, although symptoms commonly begin in the first decade of life. Symptoms include exercise intolerance (pain when exercising) and muscle weakness, which may worsen in the patient’s 40s or 50s. Most individuals are able to tolerate mild exercise and stay physically fit. Life expectancy is not affected. It is not currently possible to predict how severe the disease will be based on the inherited variants. GSD5 may affect people of any ethnicity, but it is more common among Sephardic Jewish individuals from Iran, Iraq and Syria.

For information about carrier frequency and residual risk, please see the residual risk table.