Familial hyperglucagonemia--an autosomal dominant disorder.

Basal immunoreactive glucagon was elevated in four of nine asymptomatic relatives of a patient with glucagonoma. Immunoreactive glucagon remained elevated throughout 22 to 25 hours of continuous observation. Glucagon responses to intravenous glucose and arginine or mixed meals (or both) were abnormal, whereas glucose and insulin responses were normal. Gel filtration of plasma revealed that over 85 per cent of the four relatives' immunoreactive glucagon had a molecular weight of greater than 9000 daltons whereas that of 70 per cent of the patients with glucagonoma had a molecular weight of 3500 daltons, with the remainder eluting in the area of 9000 daltons. Pancreatic angiograms and hepatic scintiscans were normal in all four relatives. The data suggest an autosomal dominant transmission of hyperglucagonemia in this family. Immunoreactive glucagon with a molecular weight of 3500 or 9000 daltons appears to be required for the development of the clinical glucagonoma syndrome.