title: Congenital hyperinsulinism caused by hexokinase I expression or glucokinase-activating mutation in a subset of β-cells.
abstract: Congenital hyperinsulinism causes persistent hypoglycemia in neonates and infants. Most often, uncontrolled insulin secretion (IS) results from a lack of functional K(ATP) channels in all β-cells or only in β-cells within a resectable focal lesion. In more rare cases, without K(ATP) channel mutations, hyperfunctional islets are confined within few lobules, whereas hypofunctional islets are present throughout the pancreas. They also can be cured by selective partial pancreatectomy; however, unlike those with a K(ATP) focal lesion, they show clinical sensitivity to diazoxide. Here, we characterized in vitro IS by fragments of pathological and adjacent normal pancreas from six such cases. Responses of normal pancreas were unremarkable. In pathological region, IS was elevated at 1 mmol/L and was further increased by 15 mmol/L glucose. Diazoxide suppressed IS and tolbutamide antagonized the inhibition. The most conspicuous anomaly was a large stimulation of IS by 1 mmol/L glucose. In five of six cases, immunohistochemistry revealed undue presence of low-K(m) hexokinase-I in β-cells of hyperfunctional islets only. In one case, an activating mutation of glucokinase (I211F) was found in pathological islets only. Both abnormalities, attributed to somatic genetic events, may account for inappropriate IS at low glucose levels by a subset of β-cells. They represent a novel cause of focal congenital hyperinsulinism.
authors.affiliation: Unit of Endocrinology and Metabolism, University of Louvain, Faculty of Medicine, Brussels, Belgium. jean-claude.henquin@uclouvain.be
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Henquin
authors.forename: Christine
authors.initials: C
authors.lastname: Sempoux
authors.forename: Joelle
authors.initials: J
authors.lastname: Marchandise
authors.forename: Sebastien
authors.initials: S
authors.lastname: Godecharles
authors.forename: Yves
authors.initials: Y
authors.lastname: Guiot
authors.forename: Myriam
authors.initials: M
authors.lastname: Nenquin
authors.forename: Jacques
authors.initials: J
authors.lastname: Rahier
mesh_terms: D019943:Amino Acid Substitution; D003981:Diazoxide; D005941:Glucokinase / Q000235:genetics* / Q000378:metabolism; D006593:Hexokinase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006946:Hyperinsulinism / Q000151:congenital* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D007004:Hypoglycemic Agents; D007231:Infant, Newborn; D007328:Insulin / Q000097:blood / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D009154:Mutation; D014044:Tolbutamide
chemical_list: D007004:Hypoglycemic Agents; D007328:Insulin; D014044:Tolbutamide; C472074:HK1 protein, human; D006593:Hexokinase; D005941:Glucokinase; D003981:Diazoxide