Characterization of genes encoding the pancreatic beta-cell ATP-sensitive K+ channel in persistent hyperinsulinemic hypoglycemia of infancy in Japanese patients.
Persistent hyperinsulinemic hypoglycemia of infancy (PHHI) is a genetic disorder characterized by unregulated insulin secretion and profound hypoglycemia. Recently, mutations of SUR1 and Kir6.2, which constitute the pancreatic beta-cell ATP-sensitive potassium (K(ATP)) channel, have been shown to be associated with familial PHHI in certain ethnic groups. In the present study, we examined clinical symptoms, therapy, and variations in the SUR1 and Kir6.2 genes in eight Japanese patients with PHHI. Four patients were being treated with pharmacological agents and the other four had required pancreatectomy to normalize glucose levels. There was no difference in timing of the onset of hypoglycemia between the groups. There also was no difference in severity between the two groups, as assessed by blood glucose levels, plasma insulin levels, and birth weight. However, all of the pancreatectomized patients and none of the medically treated group had presented with seizures. By genetic screening, we found eleven nucleotide substitutions in the SUR1 gene, three of which result in amino acid changes, and three nucleotide substitutions in the Kir6.2 gene, two of which result in amino acid changes, but all of these genetic variants had been previously reported in normal subjects. These results indicate that the mechanism of hypoglycemia in these patients is different from those previously reported in PHHI patients, giving further support to the view that PHHI is a heterogeneous disorder.
Department of Pediatrics, Chiba University School of Medicine, Japan.
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T
Someya
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Miki
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Sugihara
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Minagawa
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Yasuda
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Kohno
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Seino
D018528:ATP-Binding Cassette Transporters; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000293:Adolescent; D001724:Birth Weight; D001786:Blood Glucose / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D005260:Female; D014644:Genetic Variation; D006801:Humans; D006946:Hyperinsulinism / Q000150:complications / Q000235:genetics*; D007003:Hypoglycemia / Q000209:etiology / Q000235:genetics*; D007223:Infant; D007328:Insulin / Q000097:blood; D007515:Islets of Langerhans / Q000737:chemistry*; D008297:Male; D009154:Mutation; D016133:Polymerase Chain Reaction; D015221:Potassium Channels / Q000235:genetics*; D024661:Potassium Channels, Inwardly Rectifying; D011955:Receptors, Drug / Q000235:genetics; D064233:Sulfonylurea Receptors
C577507:ABCC8 protein, human; D018528:ATP-Binding Cassette Transporters; D001786:Blood Glucose; D007328:Insulin; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors; D000255:Adenosine Triphosphate