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 administered parenterally.