Clinical, histopathological and molecular aspects of glycogen storage disease type VII: A review of the UK experience

Glycogen storage disease type VII (GSDVII) is a metabolic myopathy characterized by phosphofructokinase deficiency resulting in impaired conversion of fructose-6-phosphate to fructose-1.6-diphosphate, affecting both anaerobic and aerobic glycolysis. It is a very rare condition with only few published case series. We present data from 6 affected individuals, including clinical, histopathological and molecular genetic aspects. Patients report functional improvement with fasting, and ingestion of fat and protein. Carbohydrate intake worsens the symptoms in 3 of the patients, resulting in an ‘out of wind phenomenon’. Alcohol intake worsened symptoms in one patient. A “second wind” phenomenon description was reported by two patients although we were unable to demonstrate it with a walking assessment.