Congenital Hyperinsulinism and Long QT Syndrome Attributable to a Variant in KCNE1.

Introduction: This is a report of a child with congenital hyperinsulinism associated with a loss-of-function variant in KCNE1. KCNE1 encodes a human potassium channel accessory (beta) subunit that modulates potassium channel Kv7.1 (encoded by KCNQ1).

Etiology of the Neonatal Hypoglycemias.

To provide a more appropriate foundation for dealing with the problem of hypoglycemia in newborn infants, this article focuses on the mechanisms which underlie the various forms of neonatal hypoglycemia and discusses their implications for newborn care. Evidence indicates that all of the major forms of neonatal hypoglycemia are the result of hyperinsulinism due to dysregulation of pancreatic islet insulin secretion. Based on these observations, the authors propose that routine measurement of B-hydroxybutyrate should be considered an essential part of glucose monitoring in newborn infants.

Role of beta-hydroxybutyrate measurement in the evaluation of plasma glucose concentrations in newborn infants.

Objective: The Glucose in Well Babies (GLOW) Study showed that there are two phases of low glucose concentrations in healthy newborn infants: an initial phase in which plasma concentrations of ketones are low; and a second phase in which low glucose concentrations are accompanied by elevated concentrations of ketones. The implications of these two phases for the brain differ depending on whether ketones are available as alternative substrate for brain metabolism. The purpose of this study was to estimate the duration of these two phases of neonatal low glucose concentrations in 66 healthy breastfed newborns from the GLOW Study during the first 5 days of life.

Phenotypic Characterization of Congenital Hyperinsulinism Due to Novel Activating Glucokinase Mutations.

Unlabelled: The importance of glucokinase (GK) in the regulation of insulin secretion has been highlighted by the phenotypes of individuals with activating and inactivating mutations in the glucokinase gene (GCK). Here we report 10 individuals with congenital hyperinsulinism (HI) caused by eight unique activating mutations of GCK. Six are novel and located near previously identified activating mutations sites.

International Guidelines for the Diagnosis and Management of Hyperinsulinism.

Background: Hyperinsulinism (HI) due to dysregulation of pancreatic beta-cell insulin secretion is the most common and most severe cause of persistent hypoglycemia in infants and children. In the 65 years since HI in children was first described, there has been a dramatic advancement in the diagnostic tools available, including new genetic techniques and novel radiologic imaging for focal HI; however, there have been almost no new therapeutic modalities since the development of diazoxide.

Summary: Recent advances in neonatal research and genetics have improved our understanding of the pathophysiology of both transient and persistent forms of neonatal hyperinsulinism.

New approaches to screening and management of neonatal hypoglycemia based on improved understanding of the molecular mechanism of hypoglycemia.

For the past 70 years, controversy about hypoglycemia in newborn infants has focused on a numerical "definition of neonatal hypoglycemia", without regard to its mechanism. This ignores the purpose of screening newborns for hypoglycemia, which is to identify those with pathological forms of hypoglycemia and to prevent hypoglycemic brain injury. Recent clinical and basic research indicates that the three major forms of neonatal hypoglycemia are caused by hyperinsulinism (recognizing also that other rare hormonal or metabolic conditions may also present during this time frame).

Case presentation of 8-year follow up of recurrent malignant duodenal Insulinoma and lymph node metastases and literature review of malignant Insulinoma management.

Background: Insulinoma is an uncommon insulin-secreting neuroendocrine tumor that presents with severe recurrent hypoglycemia. Although cases of extrapancreatic insulinomas have been reported, the majority of insulinomas occur in the pancreas. The number of reported cases of ectopic insulinomas with follow-up assessments is limited and they do not report disease recurrence.

Congenital Hyperinsulinism: An Historical Perspective.

Congenital hyperinsulinism is the most common cause of persistent hypoglycemia in neonates, infants, and children. Since the first case descriptions in the 1950s, the field has advanced significantly. It was the development of the insulin radioimmunoassay by Yalow and Berson a decade later that made it possible to demonstrate that this form of persistent hypoglycemia was caused by insulin, and a few years later, Drash described the successful treatment of children with hyperinsulinism with the antihypertensive diazoxide, which until today remains the only approved treatment for hyperinsulinism.

Mosaic GLUD1 Mutations Associated with Hyperinsulinism Hyperammonemia Syndrome.

Introduction: The hyperinsulinemia-hyperammonemia syndrome (HIHA) is the second most common cause of congenital hyperinsulinism and is caused by activating heterozygous missense mutations in GLUD1. In the majority of HIHA cases, the GLUD1 mutation is found to be de novo. We have identified 3 patients in whom clinical evaluation was suggestive of HIHA but with negative mutation analysis in peripheral blood DNA for GLUD1 as well as other known HI genes.

Localized islet nuclear enlargement hyperinsulinism (LINE-HI) due to ABCC8 and GCK mosaic mutations.

Objective: Congenital hyperinsulinism (HI) is the most common cause of persistent hypoglycemia in children. In addition to typical focal or diffuse HI, some cases with diazoxide-unresponsive congenital HI have atypical pancreatic histology termed Localized Islet Nuclear Enlargement (LINE) or mosaic HI, characterized by histologic features similar to diffuse HI, but confined to only a region of pancreas. Our objective was to characterize the phenotype and genotype of children with LINE-HI.

Advances in Understanding the Mechanism of Transitional Neonatal Hypoglycemia and Implications for Management.

Our lack of basic knowledge about the basic mechanisms of transitional hypoglycemia and other forms of hypoglycemia in newborns underlies the ongoing controversies over standards for managing these conditions. To address this deficiency, the authors evaluated regulation of insulin secretion in fetal, newborn, and adult rats. The results demonstrate that transitional hypoglycemia in normal neonates and persistent hypoglycemia in high-risk infants both reflect altered beta-cell insulin regulation.

Decreased KATP Channel Activity Contributes to the Low Glucose Threshold for Insulin Secretion of Rat Neonatal Islets.

Transitional hypoglycemia in normal newborns occurs in the first 3 days of life and has clinical features consistent with hyperinsulinism. We found a lower threshold for glucose-stimulated insulin secretion from freshly isolated embryonic day (E) 22 rat islets, which persisted into the first postnatal days. The threshold reached the adult level by postnatal day (P) 14.

Novel dominant K channel mutations in infants with congenital hyperinsulinism: Validation by in vitro expression studies and in vivo carrier phenotyping.

Inactivating mutations in the genes encoding the two subunits of the pancreatic beta-cell K channel, ABCC8 and KCNJ11, are the most common finding in children with congenital hyperinsulinism (HI). Interpreting novel missense variants in these genes is problematic, because they can be either dominant or recessive mutations, benign polymorphisms, or diabetes mutations. This report describes six novel missense variants in ABCC8 and KCNJ11 that were identified in 11 probands with congenital HI.

Mechanisms of octanoic acid potentiation of insulin secretion in isolated islets.

A potentiating effect of medium-chain triglycerides on glucose-stimulated insulin secretion (GSIS) has been observed since the 1960s. Subsequent observations identified octanoic acid (OA), the main component of medium-chain triglyceride, as the potentiator of GSIS, but the mechanism was unclear. We used wild-type (WT), short-chain 3-hydroxyacyl-CoA dehydrogenase knockout (), and sulfonylurea receptor 1 knockout () mouse islets to define the mechanism of OA potentiation of insulin secretion.

Hyperinsulinemic hypoglycemia in seven patients with de novo NSD1 mutations.

Sotos syndrome is an overgrowth syndrome characterized by distinctive facial features and intellectual disability caused by haploinsufficiency of the NSD1 gene. Genotype-phenotype correlations have been observed, with major anomalies seen more frequently in patients with 5q35 deletions than those with point mutations in NSD1. Though endocrine features have rarely been described, transient hyperinsulinemic hypoglycemia (HI) of the neonatal period has been reported as an uncommon presentation of Sotos syndrome.

Glutamate dehydrogenase: Structure of a hyperinsulinism mutant, corrections to the atomic model, and insights into a regulatory site.

Mammalian glutamate dehydrogenase (GDH) has complex allosteric regulation and the loss of GTP inhibition causes the hyperinsulinism/hyperammonemia syndrome (HHS) where insulin is hypersecreted upon consumption of protein. The archetypical HHS lesion is H454Y and lies in the GTP binding pocket. To better understand the mechanism of HHS, we determined the crystal structure of H454Y.

Surgical treatment of congenital hyperinsulinism: Results from 500 pancreatectomies in neonates and children.

Background: Congenital Hyperinsulinism (HI) causes severe hypoglycemia in neonates and children. We reviewed our experience with pancreatectomy for the various types of HI.

Methods: From 1998 to 2018, 500 patients with HI underwent pancreatectomy: 246 for focal HI, 202 for diffuse HI, 37 for atypical HI (16 for Localized Islet Nuclear Enlargement [LINE], 21 for Beckwith-Wiedemann Syndrome), and 15 for insulinoma.

Congenital Hyperinsulinism in Infants with Turner Syndrome: Possible Association with Monosomy X and KDM6A Haploinsufficiency.

Background: Previous case reports have suggested a possible association of congenital hyperinsulinism with Turner syndrome.

Objective: We examined the clinical and molecular features in girls with both congenital hyperinsulinism and Turner syndrome seen at The Children's Hospital of Philadelphia (CHOP) between 1974 and 2017.

Methods: Records of girls with hyperinsulinism and Turner syndrome were reviewed.

Clinical heterogeneity of hyperinsulinism due to HNF1A and HNF4A mutations.

Background: Dominant inactivating mutations in HNF1A and HNF4A have been described to cause hyperinsulinism (HI) before evolving to diabetes. However, information available in the literature regarding the clinical phenotype is limited.

Objective: To report the prevalence of HNF1A and HNF4A mutations in a large cohort of children with HI, and to describe their genotypes and phenotypes.

Regulation of K Channel Trafficking in Pancreatic β-Cells by Protein Histidine Phosphorylation.

Protein histidine phosphatase 1 (PHPT-1) is an evolutionarily conserved 14-kDa protein that dephosphorylates phosphohistidine. mice were generated to gain insight into the role of PHPT-1 and histidine phosphorylation/dephosphorylation in mammalian biology. mice exhibited neonatal hyperinsulinemic hypoglycemia due to impaired trafficking of K channels to the plasma membrane in pancreatic β-cells in response to low glucose and leptin and resembled patients with congenital hyperinsulinism (CHI).

Glutamate Dehydrogenase, a Complex Enzyme at a Crucial Metabolic Branch Point.

In-vitro, glutamate dehydrogenase (GDH) catalyzes the reversible oxidative deamination of glutamate to α-ketoglutarate (α-KG). GDH is found in all organisms, but in animals is allosterically regulated by a wide array of metabolites. For many years, it was not at all clear why animals required such complex control.

Functional and Metabolomic Consequences of K Channel Inactivation in Human Islets.

Loss-of-function mutations of β-cell K channels cause the most severe form of congenital hyperinsulinism (KHI). KHI is characterized by fasting and protein-induced hypoglycemia that is unresponsive to medical therapy. For a better understanding of the pathophysiology of KHI, we examined cytosolic calcium ([Ca] ), insulin secretion, oxygen consumption, and [U-C]glucose metabolism in islets isolated from the pancreases of children with KHI who required pancreatectomy.

A severe case of hyperinsulinism due to hemizygous activating mutation of glutamate dehydrogenase.

Activating mutations in the GLUD1 gene, which encodes glutamate dehydrogenase (GDH), result in the hyperinsulinism-hyperammonemia syndrome. GDH is an allosterically regulated enzyme responsible for amino acid-mediated insulin secretion via the oxidative deamination of glutamate to 2-oxoglutarate, leading to ATP production and insulin release. This study characterizes a novel combination of mutations in GLUD1 found in a neonate who presented on the first day of life with severe hypoglycemia, hyperammonemia, and seizures.