Branching enzyme-deficiency glycogenosis: studies in therapy.

Type IV glycogen storage disease is caused by a deficiency of the branching enzyme, oc-1,4-glucan: ox-1,4-glucan 6-glucosyltransferase, EC 2.4.1.18(Brown and Brown, 1966); and is characterized by the accumulation in liver, spleen, and other organs of glycogen with an abnormal structure.This glycogen has long outer chains, relatively few branch points, and gives a blue colour with iodine.It thus resembles amylopectin, and the disease is sometimes called amylopectinosis.The disease is rare, and only 4 patients have been described (Andersen, 1956;Sidbury et al., 1962;Brown and Brown, 1966; Holleman, van der Haar, and de Vaan, 1966).We present a fifth patient, a sib of the patient described by Holleman et al. (1966).The diagnosis was made during life, by the assay of the branching enzyme activity in leucocytes.An attempt was made to treat the child with oc-glucosidase, and with zinc-glucagon, both ad- ministered parenterally.Case Report This boy was referred at 5 months, with symptoms similar to those of his elder brother who had died aged 6 months (Holleman et al., 1966).The paternal grand- mother and the maternal grandfather of the patient are first cousins.The mother had 4 pregnancies: 1 ending in abortion, 1 in an anencephalic child, and 2 in patients with 'amylopectinosis'.Birthweight was 4 *7 kg.On admission he was wasted, and the abdomen was distended by an enlarged firm liver.There was no evidence of mental retardation.He made few spontaneous movements, muscle tone was poor, and tendon reflexes depressed.The head was dolicho- cephalic with normal circumference; there was epicanthus and convergent strabismus.The clinical course was that of progressive cirrhosis of the liver with wasting, ascites, splenomegaly, and intestinal haemorrhages.Hypoglycaemic attacks did