Rare forms of congenital hyperinsulinism.

Rare forms of congenital hyperinsulinism (CHI) are caused by mutations in GLUD1 (encoding glutamate dehydrogenase), GCK (encoding glucokinase), HADH (encoding for L-3-hydroxyacyl-CoA dehydrogenase), SLC16A1 (encoding the monocarboxylat transporter 1), HNF4A (encoding hepatocyte nuclear factor 4α) or UCP2 (encoding mitochondrial uncoupling protein 2). The clinical presentation is very heterogeneous in regards to age of onset, severity, and manner of symptoms, as well as the response to medical treatment. Special individual characteristics have to be accounted in diagnosis and treatment. Diazoxide is the first-line drug for the rare forms of CHI for long-term treatment but is not entirely effective in some of these rarer defects (GCK, MCT1). The use of diazoxide is often limited by side effects and the use of octreotide as second-line drug has to be considered. A near-total pancreatectomy is only reserved for patients with diffuse disease and resistance to medical treatment as a last resort. Patients with CHI should be managed by centers with a highly experienced team in diagnostic work-up and treatment of this disease.