Persistent hypoglycaemia due to hyperinsulinism in newborns and infants.

Persistent hyperinsulinemic hypoglycaemia of infancy (PHHI) is the most fre quent cause of hypoglycaemia in infancy. Clinical presentation is heterogen eous with variable onset of hypoglycaemia and response to diazoxide, and pr esence of sporadic or familial forms. Underlying histopathological lesions can be focal or diffuse. Focal lesions are characterised by focal hyperplas ia of pancreatic islet-like cells, whereas diffuse lesions implicate the wh ole pancreas. The distinction between the two forms is important because su rgical treatment and genetic counselling are radically different Focal lesi ons correspond to somatic defects which are totally cured by limited pancre atic resection, whereas diffuse lesions require a subtotal pancreatectomy e xposing to high risk of diabetes mellitus. Diffuse lesions are due to funct ional abnormalities involving several genes and different transmission form s. Recessively inherited PHHI have been attributed to homozygote mutations for the beta-cell sulfonylurea receptor (SUR1) or the inward-rectifying pot assium-channel (Kir6.2) genes. Dominantly inherited PHHI can implicate the glucokinase gene, particularly when PHHI is associated with diabetes, the g lutamate dehydrogenase gene when hyperammonaemia is associated, or another locus. (C) 1998 Elsevier, Paris.