Glycogen Storage Disease Type VIII, also known as GSD VIII or phosphorylase kinase deficiency, is a rare genetic disorder characterized by the impairment of an enzyme called phosphorylase kinase. This enzyme plays a crucial role in the breakdown and regulation of glycogen, a complex carbohydrate that serves as a primary energy source in the body.
In individuals with GSD VIII, the deficiency of phosphorylase kinase prevents the proper breakdown of glycogen into glucose molecules, leading to an abnormal accumulation of glycogen in various tissues and organs. This excess glycogen storage results in a range of symptoms and complications, including liver enlargement (hepatomegaly), low blood sugar levels (hypoglycemia), muscle weakness, and exercise intolerance.
GSD VIII is an autosomal recessive disorder, meaning that an affected individual inherits two copies of the defective gene, one from each parent. The severity of the disease can vary widely, with some individuals only experiencing mild symptoms and others facing life-threatening complications. The onset and progression of symptoms can also vary, as some individuals may present symptoms in infancy or early childhood, while others may remain asymptomatic until adulthood.
Management of GSD VIII involves a multidisciplinary approach, including dietary modifications aimed at maintaining stable blood sugar levels, regular monitoring of liver function, and genetic counseling for affected individuals and their families. Advanced treatments, such as liver transplantation, may be required in severe cases to improve long-term outcomes and prevent organ damage.
