Debrancher deficiency (oligo-1,4-glucantransferase and alpha-1,6-glucosidase deficiency; Forbes-Cori disease) is a generalized enzyme defect that blocks glycogenolysis at a branch points in the glycogen molecule, so that only the terminal chains of glycogen are accessible for hydrolysis by glycogen phosphorylase. The disease is usually a benign disorder of childhood associated with hepatomegaly and fasting hypoglycemia (attributable to the block in hepatic glycogenolysis). Because the block in muscle glycogenolysis is incomplete, symptoms of exercise intolerance typically are less prominent than in phosphorylase and phosphofructokinase (PFK) deficiencies, and muscle cramps and myoglobinuria are note features of the disorder. The most common neuromuscular feature is progressive weakness. Management includes adequate dietary carbohydrate to counter the propensity to develop hypoglycemia, frequent feedings, and a diet high in protein (e.g., 50 to 55 percent carbohydrate, 25 percent protein, 20 to 25 percent fat). Oral, uncooked cornstarch is absorbed slowly and effectively maintains blood glucose levels when administered every 6 hours.