Glycogen Storage Disease, Type VII (PFKM)

Glycogen storage disease, type VII is an autosomal recessive disorder that is caused by pathogenic variants in the gene PFKM. It is a rare disease worldwide, but is more prevalent in individuals of Ashkenazi Jewish descent. In this disease, glycogen stored in the muscles cannot be broken down efficiently, which leads to weakness and cramps during exercise. Age of onset is usually in childhood, although it can vary from infancy to adulthood. Patients can also experience hemolytic anemia, where the number of red blood cells available in the body is reduced as a result of rupture. Hemolytic anemia can lead to the development of gallstones, gout and jaundice. Very rarely, affected infants have been reported to have a severe form of the disease, leading to death in infancy. With the exception of these patients, life expectancy is not thought to be reduced. It is not currently possible to predict the severity of symptoms based on the pathogenic variants inherited.

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