[Congenital hyperinsulinism : contributions of chemistry, therapeutic response, genetics and imaging]

Congenital hyperinsulinism is the most common cause of recurrent hypoglycemia in newborns and children. Early diagnosis and rapid management are essential to avoid hypoglycaemic brain injury and later neurological complications. Management of those patients involves biological evaluation, molecular genetics, imaging techniques and surgical advances. We report the case of a newborn with recurrent hypoglycemia due to congenital hyperinsulinism (CHI) caused by a new variant in the ABCC8 gene. Fluorine 18-L-3,4 Dihydroxyphenylalanine Positron Emission Tomography (18F-DOPA PET/CT scan) reported a focal lesion at the isthmus of the pancreas which has been removed by laparoscopic surgery with a complete recovery for the patient.

Pathological features in non-neoplastic congenital and adult hyperinsulinism: from nesidioblastosis to current terminology and understanding

Nesidioblastoma and nesidioblastosis were terms given to neoplastic and non-neoplastic lesions of the pancreas associated with pancreatogenous hyperinsulinaemic hypoglycaemia. While nesidioblastoma was rapidly replaced by islet cell tumour, nesidioblastosis, defined as the proliferation of islet cells budding off from pancreatic ducts, was the diagnostic term associated with congenital hyperinsulinism of infancy (CHI) and adult non-neoplastic hyperinsulinaemic hypoglycaemia (ANHH). When it was shown that nesidioblastosis was not specific for CHI or ANHH, it was no longer applied to CHI but kept for the morphological diagnosis of ANHH. In severe CHI cases, a diffuse form with hypertrophic ß-cells in all islets can be distinguished from a focal form with hyperactive ß-cells changes in a limited adenomatoid hyperplastic area. Genetically, mutations were identified in several ß-cell genes involved in insulin secretion. Most common are mutations in the ABCC8 or KCNJ11 genes, solely affected in the diffuse form and associated with a focal maternal allelic loss on 11p15.5 in the focal form. Focal CHI can be localized by 18F-DOPA-PET and is thus curable by targeted resection. Diffuse CHI that fails medical treatment requires subtotal pancreatectomy. In ANHH, an idiopathic form can be distinguished from a form associated with gastric bypass, in whom GLP1-induced stimulation of the ß-cells is discussed. While the ß-cells in idiopathic ANHH are diffusely affected and are either hypertrophic or show only little changes, it is controversial whether there is a ß-cell increase or ß-cell hyperactivity in patients with gastric bypass. Recognizing morphological signs of ß-cell hyperactivity needs a good knowledge of the non-neoplastic endocrine pancreas across all ages.

Integration of genomic analysis and transcript expression of ABCC8 and KCNJ11 in focal form of congenital hyperinsulinism

BACKGROUND

The focal form of CHI is caused by an autosomal recessive pathogenic variant affecting the paternal homologue of genes ABCC8 or KCNJ11 and a second somatic event specifically occurring in the affected islet of Langerhans. The approach of this study was to integrate the genetic changes occurring in pancreatic focal lesions of CHI at the genomic and transcriptional level.

RESEARCH DESIGN AND METHODS

Patients receiving therapeutic surgery and with proven ABCC8 or KCNJ11 pathogenic variants were selected and analyzed for loss of heterozygosity (LOH), changes in copy number and uniparental disomy (UPD) on the short am of chromosome 11 by molecular microarray analysis and methylation-specific MLPA. Gene expression was analyzed by RT-PCR and Massive Analysis of cDNA Ends (MACE).

RESULTS

Both genes, ABCC8 and KCNJ11, are located in proximity to the Beckwith-Wiedemann (BWS) imprinting control region on chromosome 11p15. Somatic paternal uniparental isodisomy (UPD) at chromosome 11p was identified as second genetic event in focal lesions resulting in LOH and monoallelic expression of the mutated ABCC8/KCNJ11 alleles. Of five patients with samples available for microarray analysis, the breakpoints of UPD on chromosome 11p were different. Samples of two patients were analyzed further for changes in gene expression. Profound downregulation of growth suppressing genes CDKN1 and H19 was detected in focal lesions whereas growth promoting gene ASCL2 and pancreatic transcription factors of the endocrine cell lineage were upregulated.

CONCLUSIONS

Paternal UPD on the short arm of chromosome 11 appears to be the major second genetic event specifically within focal lesions of CHI but no common breakpoint for UDP can be delineated. We show for the first time upregulation of growth promoting ASCL2 (achaete-scute homolog 2) suggestive of a driving factor in postnatal focal expansion in addition to downregulation of growth suppressing genes CDKN1C and H19.

Biphasic dynamics of beta cell mass in a mouse model of congenital hyperinsulinism: implications for type 2 diabetes

AIMS/HYPOTHESIS

Acute hyperglycaemia stimulates pancreatic beta cell proliferation in the mouse whereas chronic hyperglycaemia appears to be toxic. We hypothesise that this toxic effect is mediated by increased beta cell workload, unrelated to hyperglycaemia per se.

METHODS

To test this hypothesis, we developed a novel mouse model of cell-autonomous increased beta cell glycolytic flux caused by a conditional heterozygous beta cell-specific mutation that activates glucokinase (GCK), mimicking key aspects of the rare human genetic disease GCK-congenital hyperinsulinism.

RESULTS

In the mutant mice, we observed random and fasting hypoglycaemia (random 4.5-5.4 mmol/l and fasting 3.6 mmol/l) that persisted for 15 months. GCK activation led to increased beta cell proliferation as measured by Ki67 expression (2.7% vs 1.5%, mutant and wild-type (WT), respectively, p < 0.01) that resulted in a 62% increase in beta cell mass in young mice. However, by 8 months of age, mutant mice developed impaired glucose tolerance, which was associated with decreased absolute beta cell mass from 2.9 mg at 1.5 months to 1.8 mg at 8 months of age, with preservation of individual beta cell function. Impaired glucose tolerance was further exacerbated by a high-fat/high-sucrose diet (AUC 1796 vs 966 mmol/l × min, mutant and WT, respectively, p < 0.05). Activation of GCK was associated with an increased DNA damage response and an elevated expression of Chop, suggesting metabolic stress as a contributor to beta cell death.

CONCLUSIONS/INTERPRETATION

We propose that increased workload-driven biphasic beta cell dynamics contribute to decreased beta cell function observed in long-standing congenital hyperinsulinism and type 2 diabetes.

SUR1-mutant iPS cell-derived islets recapitulate the pathophysiology of congenital hyperinsulinism

AIMS/HYPOTHESIS

Congenital hyperinsulinism caused by mutations in the KATP-channel-encoding genes (KATPHI) is a potentially life-threatening disorder of the pancreatic beta cells. No optimal medical treatment is available for patients with diazoxide-unresponsive diffuse KATPHI. Therefore, we aimed to create a model of KATPHI using patient induced pluripotent stem cell (iPSC)-derived islets.

METHODS

We derived iPSCs from a patient carrying a homozygous ABCC8V187D mutation, which inactivates the sulfonylurea receptor 1 (SUR1) subunit of the KATP-channel. CRISPR-Cas9 mutation-corrected iPSCs were used as controls. Both were differentiated to stem cell-derived islet-like clusters (SC-islets) and implanted into NOD-SCID gamma mice.

RESULTS

SUR1-mutant and -corrected iPSC lines both differentiated towards the endocrine lineage, but SUR1-mutant stem cells generated 32% more beta-like cells (SC-beta cells) (64.6% vs 49.0%, p = 0.02) and 26% fewer alpha-like cells (16.1% vs 21.8% p = 0.01). SUR1-mutant SC-beta cells were 61% more proliferative (1.23% vs 0.76%, p = 0.006), and this phenotype could be induced in SUR1-corrected cells with pharmacological KATP-channel inactivation. The SUR1-mutant SC-islets secreted 3.2-fold more insulin in low glucose conditions (0.0174% vs 0.0054%/min, p = 0.0021) and did not respond to KATP-channel-acting drugs in vitro. Mice carrying grafts of SUR1-mutant SC-islets presented with 38% lower fasting blood glucose (4.8 vs 7.7 mmol/l, p = 0.009) and their grafts failed to efficiently shut down insulin secretion during induced hypoglycaemia. Explanted SUR1-mutant grafts displayed an increase in SC-beta cell proportion and SC-beta cell nucleomegaly, which was independent of proliferation.

CONCLUSIONS/INTERPRETATION

We have created a model recapitulating the known pathophysiology of KATPHI both in vitro and in vivo. We have also identified a novel role for KATP-channel activity during human islet development. This model will enable further studies for the improved understanding and clinical management of KATPHI without the need for primary patient tissue.

Differential Morphological Diagnosis of Various Forms of Congenital Hyperinsulinism in Children

INTRODUCTION

Congenital hyperinsulinism (CHI) has diffuse (CHI-D), focal (CHI-F) and atypical (CHI-A) forms. Surgical management depends on preoperative [18F]-DOPA PET/CT and intraoperative morphological differential diagnosis of CHI forms. Objective: to improve differential diagnosis of CHI forms by comparative analysis [18F]-DOPA PET/CT data, as well as cytological, histological and immunohistochemical analysis (CHIA).

MATERIALS AND METHODS

The study included 35 CHI patients aged 3.2 ± 2.0 months; 10 patients who died from congenital heart disease at the age of 3.2 ± 2.9 months (control group). We used PET/CT, CHIA of pancreas with antibodies to ChrA, insulin, Isl1, Nkx2.2, SST, NeuroD1, SSTR2, SSTR5, DR1, DR2, DR5; fluorescence microscopy with NeuroD1/ChrA, Isl1/insulin, insulin/SSTR2, DR2/NeuroD1 cocktails.

RESULTS

Intraoperative examination of pancreatic smears showed the presence of large nuclei, on average, in: 14.5 ± 3.5 cells of CHI-F; 8.4 ± 1.1 of CHI-D; and 4.5 ± 0.7 of control group (from 10 fields of view, x400). The percentage of Isl1+ and NeuroD1+endocrinocytes significantly differed from that in the control for all forms of CHI. The percentage of NeuroD1+exocrinocytes was also significantly higher than in the control. The proportion of ChrA+ and DR2+endocrinocytes was higher in CHI-D than in CHI-F, while the proportion of insulin+cells was higher in CHI-A. The number of SST+cells was significantly higher in CHI-D and CHI-F than in CHI-A.

CONCLUSION

For intraoperative differential diagnosis of CHI forms, in addition to frozen sections, quantitative cytological analysis can be used. In quantitative immunohistochemistry, CHI forms differ in the expression of ChrA, insulin, SST and DR2. The development of a NeuroD1 inhibitor would be advisable for targeted therapy of CHI.

Intraoperative ultrasound imaging in the surgical treatment of congenital hyperinsulinism: prospective, blinded study

Background

In congenital hyperinsulinism (CHI), preoperative prediction of the histological subtype (focal, diffuse, or atypical) relies on genetics and 6-[¹⁸F]fluoro-l-3,4-dihydroxyphenylalanine (¹⁸F-DOPA) PET–CT. The scan also guides the localization of a potential focal lesion along with perioperative frozen sections. Intraoperative decision-making is still challenging. This study aimed to describe the characteristics and potential clinical impact of intraoperative ultrasound imaging (IOUS) during CHI surgery.

Methods

This was a prospective, observational study undertaken at an expert centre over a 2-year interval. IOUS was performed blinded to preoperative diagnostic test results (genetics and ¹⁸F-DOPA PET–CT), followed by unblinding and continued IOUS during pancreatic resection. Characteristics and clinical impact were assessed using predefined criteria.

Results

Eighteen consecutive, surgically treated patients with CHI, with a median age of 5.5 months, were included (focal 12, diffuse 3, atypical 3). Focal lesions presented as predominantly hypoechoic, oval lesions with demarcated or blurred margins. Patients with diffuse and atypical disease had varying echogenicity featuring stranding and non-shadowing hyperechoic foci in three of six, whereas these characteristics were absent from those with focal lesions. The blinded IOUS-based subclassification was correct in 17 of 18 patients; one diffuse lesion was misclassified as focal. IOUS had an impact on the surgical approach in most patients with focal lesions (9 of 12), and in those with diffuse (2 of 3) and atypical (2 of 3) disease when the resection site was close to the bile or pancreatic duct.

Conclusion

Uniform IOUS characteristics made all focal lesions identifiable. IOUS had a clinical impact in 13 of 18 patients by being a useful real-time supplementary modality in terms of localizing focal lesions, reducing the need for frozen sections, and preserving healthy tissue and delicate structures.

Clinical and Genetic Characterization of 153 Patients with Persistent or Transient Congenital Hyperinsulinism

CONTEXT

Major advances have been made in the genetics and classification of congenital hyperinsulinism (CHI).

OBJECTIVE

To examine the genetics and clinical characteristics of patients with persistent and transient CHI.

DESIGN

A cross-sectional study with the register data and targeted sequencing of 104 genes affecting glucose metabolism.

PATIENTS

Genetic and phenotypic data were collected from 153 patients with persistent (n = 95) and transient (n = 58) CHI diagnosed between 1972 and 2015. Of these, 86 patients with persistent and 58 with transient CHI participated in the analysis of the selected 104 genes affecting glucose metabolism, including 10 CHI-associated genes, and 9 patients with persistent CHI were included because of their previously confirmed genetic diagnosis.

MAIN OUTCOME MEASURES

Targeted next-generation sequencing results and genotype-phenotype associations.

RESULTS

Five novel and 21 previously reported pathogenic or likely pathogenic variants in ABCC8, KCNJ11, GLUD1, GCK, HNF4A, and SLC16A1 genes were found in 68% (n = 65) and 0% of the patients with persistent and transient CHI, respectively. KATP channel mutations explained 82% of the mutation positive cases.

CONCLUSIONS

The genetic variants found in this nationwide CHI cohort are in agreement with previous studies, mutations in the KATP channel genes being the major causes of the disease. Pathogenic CHI-associated variants were not identified in patients who were both diazoxide responsive and able to discontinue medication within the first 4 months. Therefore, our results support the notion that genetic testing should be focused on patients with inadequate response or prolonged need for medication.

Efficacy of Dose-Titrated Glucagon Infusions in the Management of Congenital Hyperinsulinism: A Case Series

Background: Congenital hyperinsulinism (CHI), a rare disease of excessive and dysregulated insulin secretion, can lead to prolonged and severe hypoglycemia. Dextrose infusions are a mainstay of therapy to restore normal glycemia, but can be associated with volume overload, especially in infants. By releasing intrahepatic glucose stores, glucagon infusions can reduce dependency on dextrose infusions. Recent studies have reported positive outcomes with glucagon infusions in patients with CHI; however, to date, there are no reports describing the clinical utility of titrated doses of infused glucagon to achieve glycemic stability. Objective: To assess the potential clinical utility of dose-titrated glucagon infusions in stabilizing glycemic status in pediatric patients with CHI, who were managed by medical and/or surgical approaches. Methods: Patients with CHI (N = 33), with or without mutations in the ATP-sensitive K⁺ channel genes, ABCC8, and KCNJ11 requiring glucagon by dose titration in addition to intravenous dextrose and medical therapy with diazoxide/octreotide to achieve glycemic stability were recruited. Following glucagon titration and a 24-h glucose stable period, glucose infusion rate (GIR) was reduced over a 24-h period. Achievement of glycemic stability and decrease in GIR were considered end points of the study. Results: All patients achieved glycemic stability with glucagon infusion, demonstrating clinical benefit. GIR reduced from 15.6 (4.5) to 13.4 (4.6) mg/kg/min mean (SD) (p = 0.00019 for difference; n = 32; paired t-test) over 24 h. By univariate analysis, no individual baseline characteristic was associated with changes in the GIR. However, by baseline-adjusted modeling, mutational status of the patient (p = 0.011) was inversely associated with a reduction in GIR. Adverse events were infrequent with diarrhea possibly attributed to glucagon treatment in 1 patient. With long-term treatment following GIR reduction, necrolytic migratory erythema was observed in another patient. Conclusion: These data suggest that dose-titrated glucagon infusion therapy aids hypoglycemia prevention and reduction in GIR in the clinical management of patients with CHI.

Clinical and enzymatic phenotypes in congenital hyperinsulinemic hypoglycemia due to glucokinase-activating mutations: A report of two cases and a brief overview of the literature

AIMS/INTRODUCTION

The principal aim of this study was to investigate the clinical, genetic and functional characteristics of two cases of congenital hyperinsulinism (CHI) caused by glucokinase (GCK) mutations in young patients.

MATERIALS AND METHODS

Novel mutations were detected by CHI next-generation sequencing, and the kinetic parameters and thermal stability of recombinant wild-type and mutant glucokinase were determined in vitro. In addition, 18 naturally occurring GCK-CHI mutations reported previously were also summarized.

RESULTS

A de novo mutation (M197V) was found in a 17-year-old male with an epilepsy history, whereas an autosomal dominant mutation (K90R) was found in a 20-year-old female with inherited asymptomatic hypoglycemia. Kinetic analysis showed increased enzyme activity for both mutants (RAI 4.7 for M197V and 1.6 for K90R) and enhanced thermal stability for the M197V mutant. However, of all the GCK-CHI mutants, the increase in enzyme activity (RAI between 1.6 and 130) did not correlate strongly with the severity of hypoglycemia. The de novo group (7/19) showed distinctive phenotypes from the autosomal dominant group (12/19), such as a higher proportion of diazoxide unresponsiveness (28.6% vs 0%), a higher incidence of macrosomia (85.7% vs 40%) and a rarer incidence of adulthood onset (0% vs 25%).

CONCLUSIONS

The clinical phenotypes of GCK-CHIs were highly heterogeneous. We have identified two novel GCK-CHI mutations in young patients and investigated their pathogenicity by enzyme kinetic analysis, which expanded the spectrum of this rare disease.

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. Eight cases of 5q35 deletions and one patient with an intragenic NSD1 mutation with transient HI have been reported. Here, we describe seven individuals with HI caused by NSD1 gene mutations with three having persistent hyperinsulinemic hypoglycemia. These patients with persistent HI and Sotos syndrome caused by NSD1 mutations, further dispel the hypothesis that HI is due to the deletion of other genes in the deleted 5q35 region. These patients emphasize that NSD1 haploinsufficiency is sufficient to cause HI, and suggest that Sotos syndrome should be considered in patients presenting with neonatal HI. Lastly, these patients help extend the phenotypic spectrum of Sotos syndrome to include HI as a significant feature.

Pancreatic uptake and radiation dosimetry of 6-[18F]fluoro-L-DOPA from PET imaging studies in infants with congenital hyperinsulinism

METHODS

After injecting 25.6 ± 8.8 MBq (0.7 ± 0.2 mCi) of 18F-Fluoro-L-DOPA intravenously, three static PET scans were acquired at 20, 30, and 40 min post injection in 3-D mode on 10 patients (6 male, 4 female) with congenital hyperinsulinism. Regions of interest (ROIs) were drawn over several organs visible in the reconstructed PET/CT images and time activity curves (TACs) were generated. Residence times were calculated using the TAC data. The radiation absorbed dose for the whole body was calculated by entering the residence times in the OLINDA/EXM 1.0 software.

RESULTS

The mean residence times for the 18F-Fluoro-L-DOPA in the liver, lungs, kidneys, muscles, and pancreas were 11.54 ± 2.84, 1.25 ± 0.38, 4.65 ± 0.97, 17.13 ± 2.62, and 0.89 ± 0.34 min, respectively. The mean effective dose equivalent for 18F-Fluoro-L-DOPA was 0.40 ± 0.04 mSv/MBq. The CT scan used for attenuation correction delivered an additional radiation dose of 5.7 mSv. The organs receiving the highest radiation absorbed dose from 18F-Fluoro-L-DOPA were the urinary bladder wall (2.76 ± 0.95 mGy/MBq), pancreas (0.87 ± 0.30 mGy/MBq), liver (0.34 ± 0.07 mGy/MBq), and kidneys (0.61 ± 0.11 mGy/MBq). The renal system was the primary route for the radioactivity clearance and excretion.

CONCLUSIONS

The estimated radiation dose burden from 18F-Fluoro-L-DOPA is relatively modest to newborns.

Atypical Forms of Congenital Hyperinsulinism in Infancy Are Associated With Mosaic Patterns of Immature Islet Cells

OBJECTIVES

We aimed to characterize mosaic populations of pancreatic islet cells from patients with atypical congenital hyperinsulinism in infancy (CHI-A) and the expression profile of NKX2.2, a key transcription factor expressed in β-cells but suppressed in δ-cells in the mature pancreas.

PATIENTS/METHODS

Tissue was isolated from three patients with CHI-A following subtotal pancreatectomy. CHI-A was diagnosed on the basis of islet mosaicism and the absence of histopathological hallmarks of focal and diffuse CHI (CHI-D). Immunohistochemistry was used to identify and quantify the proportions of insulin-secreting β-cells and somatostatin-secreting δ-cells in atypical islets, and results were compared with CHI-D (n = 3) and age-matched control tissues (n = 3).

RESULTS

In CHI-A tissue, islets had a heterogeneous profile. In resting/quiescent islets, identified by a condensed cytoplasm and nuclear crowding, β-cells were reduced to <50% of the total cell numbers in n = 65/70 islets, whereas δ-cell numbers were increased with 85% of islets (n = 49/57) containing >20% δ-cells. In comparison, all islets in control tissue (n = 72) and 99% of CHI-D islets (n = 72) were composed of >50% β-cells, and >20% δ-cells were found only in 12% of CHI-D (n = 8/66) and 5% of control islets (n = 3/60). Active islets in CHI-A tissue contained proportions of β-cells and δ-cells similar to those of control and CHI-D islets. Finally, when compared with active islets, quiescent islets had a twofold higher prevalence of somatostatin/NKX2.2+ coexpressed cells.

CONCLUSIONS

Marked increases in NKX2.2 expression combined with increased numbers of δ-cells strongly imply that an immature δ-cell profile contributed to the pathobiology of CHI-A.

Enhanced Islet Cell Nucleomegaly Defines Diffuse Congenital Hyperinsulinism in Infancy but Not Other Forms of the Disease

OBJECTIVES

To quantify islet cell nucleomegaly in controls and tissues obtained from patients with congenital hyperinsulinism in infancy (CHI) and to examine the association of nucleomegaly with proliferation.

METHODS

High-content analysis of histologic sections and serial block-face scanning electron microscopy were used to quantify nucleomegaly.

RESULTS

Enlarged islet cell nuclear areas were 4.3-fold larger than unaffected nuclei, and the mean nuclear volume increased to approximately threefold. Nucleomegaly was a normal feature of pediatric islets and detected in the normal regions of the pancreas from patients with focal CHI. The incidence of nucleomegaly was highest in diffuse CHI (CHI-D), with more than 45% of islets containing two or more affected cells. While in CHI-D nucleomegaly was negatively correlated with cell proliferation, in all other cases, there was a positive correlation.

CONCLUSIONS

Increased incidence of nucleomegaly is pathognomonic for CHI-D, but these cells are nonproliferative, suggesting a novel role in the pathobiology of this condition.

Persistent hyperinsulinemic hypoglycemia of infancy: a clinical and pathological study of 19 cases in a single institution

OBJECTIVE

To study the clinical and pathological features of persistent hyperinsulinemic hypoglycemia of infancy.

METHOD

The clinical and pathological data of 19 cases of persistent hyperinsulinemic hypoglycemia of infancy were retrieved and reviewed from the medical records in Children's Hospital of Fudan University.

RESULTS

There were 13 boys and 6 girls. The age interval was from 16 days to 7 months, and the average age was 2.71 ± 2.23 months. The blood glucose concentrations ranged from 0.57 to 3.0 mmol/L (average value 1.60 ± 0.75 mmol/L) and the serum insulin concentrations ranged from 3.1 to 79.4 uIU/ml (average value 27.89 ± 21.81 uIU/ml) at the time of one week before operation. The size of lesion was between 2 cm to 6.5 cm in maximum diameter (average value 4.04 ± 1.18 cm). 19 cases were divided into three types according to the pathological classification criteria: focal type (1 case), diffuse type (17 cases) and atypical type (1 case). The enucleation of the nodule was given for the patient of focal type and subtotal pancreatectomy was administrated for diffuse and atypical type patients. The blood glucose concentrations ranged from 3.0 to 12.4 mmol/L (average value 6.21 ± 2.69 mmol/L) at the time of one month after operation. The difference between the preoperative blood glucose concentrations and the postoperative blood glucose concentrations was statistically significant (1.6037 ± 0.7458 mmol/L vs. 6.2105 ± 2.6882 mmol/L, P<0.05). Insulin was positive for the multiple pancreatic islets, and the ki-67 index was between 5% and 8%. P57(kip2) was negative. 19 patients were followed up for a period of 2 to 38 months. 13 cases recovered well without any complications, and 6 cases had postoperative hyperglycemia and need a medication to control the blood glucose concentrations.

CONCLUSION

Persistent hyperinsulinemic hypoglycemia of infancy mainly occurred in infants. Boys had the predominance and the most common pathological type was the diffuse type. The different surgical methods (focal type with lesion enucleation, diffuse and atypical type with subtotal pancreatectomy), were effective for different patients, and most of patients had a good prognosis. Early diagnosis and appropriate treatment to maintain euglycemia remained the mainstay of management to prevent postoperative complications. Therefore, the correct pathological classification could help clinicians to find effective treatment and improve the outcome.

Dipeptidyl peptidase-4 expression in pancreatic tissue from patients with congenital hyperinsulinism

Congenital hyperinsulinism (CHI) is caused by unregulated insulin release and leads to hyperinsulinaemic-hypoglycaemia (HH). Glucagon like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), peptide YY (PYY) and the enzyme; dipeptidyl peptidase-4 (DPP-4) all regulate appetite and glucose homeostasis. These proteins have been identified as possible contributors to HH but the mechanism remains poorly understood. We aimed to look at the expression pattern of pancreatic DPP-4 in children with focal and diffuse CHI (FCHI and DCHI, respectively). Using immunohistochemistry; we determined DPP-4 expression patterns in the pancreas of CHI patients. DPP-4 was found to be expressed in the pancreatic β, α and δ-cells in and around the focal area. However, it was predominantly co-localised with β-cells in the paediatric tissue samples. Additionally, proliferating β-cells expressed DPP-4 in DCHI, which was absent in the FCHI pancreas. Insulin was found to be present in the exocrine acini and duct cells of the DCHI pancreas suggestive of exocrine to endocrine transdifferentiation. Furthermore, 6 medically-unresponsive DCHI pancreatic samples showed an up-regulation of total pancreatic DPP-4 expression. In conclusion; the expression studies have shown DPP-4 to be altered in HH, however, further work is required to understand the underlying role for this enzyme.

Molecular mechanisms of congenital hyperinsulinism

Congenital hyperinsulinism (CHI) is a complex heterogeneous condition in which insulin secretion from pancreatic β-cells is unregulated and inappropriate for the level of blood glucose. The inappropriate insulin secretion drives glucose into the insulin-sensitive tissues, such as the muscle, liver and adipose tissue, leading to severe hyperinsulinaemic hypoglycaemia (HH). At a molecular level, genetic abnormalities in nine different genes (ABCC8, KCNJ11, GLUD1, GCK, HNF4A, HNF1A, SLC16A1, UCP2 and HADH) have been identified which cause CHI. Autosomal recessive and dominant mutations in ABCC8/KCNJ11 are the commonest cause of medically unresponsive CHI. Mutations in GLUD1 and HADH lead to leucine-induced HH, and these two genes encode the key enzymes glutamate dehydrogenase and short chain 3-hydroxyacyl-CoA dehydrogenase which play a key role in amino acid and fatty acid regulation of insulin secretion respectively. Genetic abnormalities in HNF4A and HNF1A lead to a dual phenotype of HH in the newborn period and maturity onset-diabetes later in life. This state of the art review provides an update on the molecular basis of CHI.

Clinical and histological heterogeneity of congenital hyperinsulinism due to paternally inherited heterozygous ABCC8/KCNJ11 mutations

CONTEXT

Congenital hyperinsulinism (CHI) has two main histological types: diffuse and focal. Heterozygous paternally inherited ABCC8/KCNJ11 mutations (depending upon whether recessive or dominant acting and occurrence of somatic maternal allele loss) can give rise to either phenotype. However, the relative proportion of these two phenotypes in a large cohort of CHI patients due to paternally inherited heterozygous ABCC8/KCNJ11 mutations has not been reported.

OBJECTIVE

The purpose of this study is to highlight the variable clinical phenotype and to characterise the distribution of diffuse and focal disease in a large cohort of CHI patients due to paternally inherited heterozygous ABCC8/KCNJ11 mutations.

DESIGN

A retrospective chart review of the CHI patients due to heterozygous paternally inherited ABCC8/KCNJ11 mutations from 2000 to 2013 was conducted.

RESULTS

Paternally inherited heterozygous ABCC8/KCNJ11 mutations were identified in 53 CHI patients. Of these, 18 (34%) either responded to diazoxide or resolved spontaneously. Fluorine-18 l-3, 4-dihydroxyphenylalanine positron emission tomography computerised tomography 18F DOPA-PET CT) scanning in 3/18 children showed diffuse disease. The remaining 35 (66%) diazoxide-unresponsive children either had pancreatic venous sampling (n=8) or 18F DOPA-PET CT (n=27). Diffuse, indeterminate and focal disease was identified in 13, 1 and 21 patients respectively. Two patients with suspected diffuse disease were identified to have focal disease on histology.

CONCLUSIONS

Paternally inherited heterozygous ABCC8/KCNJ11 mutations can manifest as a wide spectrum of CHI with variable 18F DOPA-PET CT/histological findings and clinical outcomes. Focal disease was histologically confirmed in 24/53 (45%) of CHI patients with paternally inherited heterozygous ABCC8/KCNJ11 mutations.

Congenital hyperinsulinism in a newborn with a novel homozygous mutation (p.Q392H) in the ABCC8 gene

Congenital hyperinsulinism is the most frequent cause of persistent hypoglycemia in infancy. We present the case of a preterm, large-for-gestation-age infant with congenital hyperinsulinism who was found to have a novel p.Q392H homozygous mutation in the ABCC8 gene. The patient had severe brain damage, despite early diagnosis and appropriate management. The new mutations may provide an understanding of the prognosis and treatment of the disease. In addition, the data will help the family make informed decisions about future pregnancies.

[Malignant hypoglycaemia]

We describe the case of a 19-years old patient with seizure due to severe hypoglycaemia during general practitioner consultation. Because of hyperinsulinaemic hypoglycaemia and suspected liver metastasis a neuroendocrine hormone active tumor was suspected. After liver biopsy and CT scan a neuroendocrine pancreatic tumor could be diagnosed. Afterwards oncological therapy was induced.

Novel mutation c.597_598dup in exon 5 of ABCC8 gene causing congenital hyperinsulinism

Congenital hyperinsulinism (CHI), a clinically and genetically heterogeneous disease, characterized by the unregulated secretion of insulin from pancreatic β-cells, is the most common cause of persistent hypoglycemia in infancy. Early diagnosis and maintenance of normoglycaemia are essential to prevent adverse neurodevelopmental outcomes. The most common and severe forms of CHI are caused by inactivating mutations in ABCC8 and KCNJ11 genes, encoding the two subunits of the pancreatic β-cell ATP sensitive potassium channel (KATP). We report a case of neonatal CHI due to a novel homozygous recessive mutation in the ABCC8 gene.

Hyperinsulinaemic hypoglycaemia: genetic mechanisms, diagnosis and management

Hyperinsulinaemic hypoglycaemia (HH) is due to the unregulated secretion of insulin from pancreatic β-cells. A rapid diagnosis and appropriate management of these patients is essential to prevent the potentially associated complications like epilepsy, cerebral palsy and neurological impairment. The molecular basis of HH involves defects in key genes (ABCC8, KCNJ11, GLUD1, GCK, HADH, SLC16A1, HNF4A and UCP2) which regulate insulin secretion. The most severe forms of HH are due to loss of function mutations in ABCC8/KCNJ11 which encode the SUR1 and KIR6.2 components respectively of the pancreatic β-cell K(ATP) channel. At a histological level there are two major forms (diffuse and focal) each with a different genetic aetiology. The diffuse form is inherited in an autosomal recessive (or dominant) manner whereas the focal form is sporadic in inheritance and is localised to a small region of the pancreas. The focal form can now be accurately localised pre-operatively using a specialised positron emission tomography scan with the isotope Fluroine-18L-3, 4-dihydroxyphenyalanine (18F-DOPA-PET). Focal lesionectomy can provide cure from the hypoglycaemia. However the diffuse form is managed medically or by near total pancreatectomy (with high risk of diabetes mellitus). Recent advances in molecular genetics, imaging with 18F-DOPA-PET/CT and novel surgical techniques have changed the clinical approach to patients with HH.

The heterogeneity of focal forms of congenital hyperinsulinism

BACKGROUND

Congenital hyperinsulinism (CHI) is a cause of persistent hypoglycemia due to unregulated insulin secretion from pancreatic β-cells. Histologically, there are two major subgroups, focal and diffuse. Focal CHI is typically unresponsive to diazoxide and can be cured with surgical removal of the focal lesion.

AIMS

We report on three patients with focal CHI to illustrate the marked clinical, genetic, radiological, and histological heterogeneity.

METHODS AND RESULTS

The first two patients had focal CHI due to a paternal (c.3992-9G→A) ABCC8 mutation. One of these patients was fully responsive to a small dose (5 mg/kg · d) of diazoxide, whereas the other patient was medically unresponsive. In both patients, the focal lesions were accurately localized preoperatively by [(18)F]dihydroxyphenylalanine (DOPA) positron emission tomography (PET) and surgically resected. The third patient had a paternally inherited ABCC8 (A1493T) mutation, and the initial [(18)F]DOPA PET scan indicated extensive uptake of DOPA in the body and tail of the pancreas. However, despite surgical resection of the body and tail, this patient continued to have severe CHI. A subsequent [(18)F]DOPA PET scan now showed markedly increased DOPA uptake in the remaining body and head of the pancreas. This focal lesion occupied virtually the whole of the pancreas. conclusions: These three cases illustrate that focal lesions even with the same genotype (c.3992-9G→A) may have a different clinical presentation and that [(18)F]DOPA PET scans in very large focal lesions may be difficult to interpret.

Morphological mosaicism of the pancreatic islets: a novel anatomopathological form of persistent hyperinsulinemic hypoglycemia of infancy

BACKGROUND

Morphological studies of the pancreas in persistent hyperinsulinemic hypoglycemia of infancy (PHHI) have focused on the diagnosis of focal vs. diffuse forms, a distinction that determines the optimal surgical management. ABCC8 or KCNJ11 genomic mutations are present in most of them.

AIM

Our aim was to report a new form of PHHI with peculiar morphological and clinical characteristics.

RESEARCH DESIGN AND METHODS

Histopathological review of 217 pancreatic PHHI specimens revealed 16 cases morphologically different from diffuse and focal forms. They were analyzed by conventional microscopy, quantitative morphometry, immunohistochemistry, and in situ hybridization.

RESULTS

Their morphological peculiarity was the coexistence of two types of islet: large islets with cytoplasm-rich β-cells and occasional enlarged nuclei and shrunken islets with β-cells exhibiting little cytoplasm and small nuclei. In small islets, β-cells had abundant insulin content but limited amount of Golgi proinsulin. Large islets had low insulin storage and high proinsulin production and were mostly confined to a few lobules. No evidence for K(ATP) channels involvement or 11p15 deletion was found. Genomic mutations for ABCC8, KCNJ11, and GCK were absent. Patients had normal birth weight and late hypoglycemia onset and improved with diazoxide. Ten were cured by limited pancreatectomy. Six recurred after surgery and were medically controlled.

CONCLUSION

This new form of PHHI is characterized by a morphological mosaicism. Pathologists should recognize this mosaicism on intraoperative frozen sections because it is often curable by partial pancreatectomy. The currently unknown genetic background does not involve the classical genomic mutations responsible for diffuse and focal PHHI.

[Congenital hyperinsulinism--new causes and clinical variations]

Congenital hyperinsulinism (CHI) is a heterogeneous disease with variable onset, non- or hypoketotic hypoglycaemia, onset from birth to adulthood and a persistent, intermittent, or transient course with possible later conversion to non-autoimmune diabetes. Giving insights to beta cell function, CHI mutations are now known in eight genes (ABCC8, KCNJ11, GLUD1, GCK, HADH, SLC16A1, HNF4A and UCP2). However, 40-50% of the patients are still genetically unexplained. CHI can be dominantly or recessively inherited or may occur de novo. A number of syndromes can be associated with CHI.

[Congenital hyperinsulinism--diagnosis and treatment]

Congenital hyperinsulinism (CHI) is a rare and heterogeneous disease with a challenging diagnostic process and a need of individualised treatment of each patient. In severe, neonatal or infant CHI, differentiation between the focal and diffuse form by rapid genetics, 18F-fluoro-L-dihydroxyphenylalanine positron emission tomography/computed tomography and peroperative microscopy of frozen section allows surgeons to resect the focal lesion instead of performing subtotal pancreatectomy. Milder CHI, sometimes difficult to diagnose, is treated conservatively. In spite of all improvements, cerebral complications are still frequently seen.

[Congenital hyperinsulinism in the north-east Netherlands. Clinical features and DNA diagnostics in 22 children]

OBJECTIVE

To describe the clinical features and relevant genetic mutations in 22 children with congenital hyperinsulinism in the north-east Netherlands.

DESIGN

Retrospective, descriptive study.

METHOD

Children born between June 1988 and June 2009, who were presented at the academic medical centres of Nijmegen and Groningen were included. They were clinically suspected of having congenital hyperinsulinism and DNA diagnostics were carried out. Clinical course, laboratory results, genetic data, interventions, follow-up data and patient demographics were documented.

RESULTS

A total of 22 children from 20 families were included. Of these 22 children, 5 were born macrosomic. In 16 children the disorder was picked up within the first 4 days of life either through glucose screening of premature children or because they had symptoms. All children were treated with diazoxide; 12 (55%) did not respond to this treatment. Ultimately, 9 children underwent pancreatectomy. Five children had focal type congenital hyperinsulinism. In 15 children 13 different mutations were identified in relevant genes. We found 9 different mutations in the ABCC8-gene, including 2 novel mutations (c.2117-2A>T and c.4076C>G), 1 in the KCNJ11 gene, 1 in the GCK gene, and 2 in the GLUD1 gene. In the villages of Aalten and Silvolde a high prevalence of congenital hyperinsulinism was observed (1 in 6930), probably due to a common ancestor.

CONCLUSION

The clinical characteristics of Dutch children with congenital hyperinsulinism were comparable with those reported in other study populations. We found two novel mutations in the ABCC8 gene. The mutations in the north-east Netherlands were diverse; no one mutation occurred more frequently than any other.

Familial focal congenital hyperinsulinism

BACKGROUND

Congenital hyperinsulinism (CHI) is a cause of persistent hypoglycemia. Histologically, there are two subgroups, diffuse and focal. Focal CHI is a consequence of two independent events, inheritance of a paternal mutation in ABCC8/KCNJ11 and paternal uniparental isodisomy of chromosome 11p15 within the embryonic pancreas, leading to an imbalance in the expression of imprinted genes. The probability of both events occurring within siblings is rare.

AIM

We describe the first familial form of focal CHI in two siblings.

PATIENTS AND METHODS

The proband presented with medically unresponsive CHI. He underwent pancreatic venous sampling and Fluorine-18-L-dihydroxyphenylalanine positron emission tomography scan, which localized a 5-mm focal lesion in the isthmus of the pancreas. The sibling presented 8 yr later also with medically unresponsive CHI. An Fluorine-18-L-dihydroxyphenylalanine positron emission-computerised tomography scan showed a 7-mm focal lesion in the posterior section of the head of the pancreas. Both siblings were found to be heterozygous for two paternally inherited ABCC8 mutations, A355T and R1494W. Surgical removal of the focal lesions in both siblings cured the Hyperinsulinaemic hypoglycaemia.

CONCLUSION

This is the first report of focal CHI occurring in siblings. Genetic counseling for families of patients with focal CHI should be recommended, despite the rare risk of recurrence of this disease.

Persistent hyperinsulinemic hypoglycemia of infancy: constitutive activation of the mTOR pathway with associated exocrine-islet transdifferentiation and therapeutic implications

BACKGROUND

Amino-acids stimulate the mammalian target of rapamycin complex(mTORC)1; mTORC1 integrates amino-acid and energy-sensing pathways in beta-cells. Rapamycin inhibits mTORC1. We examined the mTOR pathway and cell cycle data in the exocrine pancreas in diffuse persistent hyperinsulinemic hypoglycemia of infancy (PHHI).

DESIGN

Tissues from two diffuse PHHI cases, one pediatric control and from adult pancreatic tissue microarray were analyzed. The case studies are newborns of non-diabetic mothers, one with SUR1 mutation, and the other with a family history of PHHI. Immunostaining for (p)-mTOR(Ser2448), phospholipase(PLD)1, cell cycle analytes ( Ki67, Skp2, p27Kip1), and insulin were performed. Cell cycle analytes were assessed by automated cellular imaging or visual quantification. Multispectral imaging of double immunostaining for insulin/p-mTOR and transmission electron microscopy (TEM) were performed.

RESULTS

Hematoxylin-eosin and insulin-staining showed beta-cell hyperplasia in the exocrine pancreas, without mass effect. Overexpression of (p)-mTOR on the plasmalemmal, but not nuclear compartment, consistent with mTORC1, was noted in acinar elements. Residual expression was noted in islets. Double immunostaining revealed occasional exocrine cells co-expressing mTOR and insulin. No such co-expressions were seen in the control. TEM showed acinar cells containing zymogen and hormone-secreting granules. No nuclear Skp2 was noted. Obversely, p27Kip1 was expressed. Mitotic index was 1/40 (0.25/10) HPF.

CONCLUSION

Morphoproteomic, histopathologic and morphometric findings in this study of diffuse PHHI coincide with existing genomic and signal transduction data in: 1) supporting a role for a constitutively activated and overexpressed mTORC1 pathway in the acinar pancreas in its pathogenesis; 2) reaffirming transdifferentiation of acinar-to-islet cells; 3) raising the possibility of rapamycin as a therapeutic option in PHHI.

Identification of two Novel Frameshift Mutations in the KCNJ11 gene in two Italian patients affected by Congenital Hyperinsulinism of Infancy

Congenital Hyperinsulinism of Infancy (CHI) is a genetically heterogeneous disorder characterized by profound hypoglycemia related to inappropriate insulin secretion. Two histopathologically and genetically distinct groups are recognized among patients with CHI due to ATP-sensitive potassium channel (KATP) defects: a diffuse type (Di-CHI), which involves the whole pancreas, and a focal form (Fo-CHI), which shows adenomatous islet-cell hyperplasia of a particular area within the normal pancreas. The beta-cell KATP channel consists of two essential subunits: Kir6.2 encoded by the KCNJ11 gene which is the pore-forming unit and belongs to the inwardly rectifying potassium channel family, and SUR1 (sulfonylurea receptor 1) encoded by the ABCC8 gene, which belongs to the ATP-binding cassette (ABC) transporter family. The KATP channel is an octameric complex of four Kir6.2 and four SUR1 subunits. More than one hundred mutations have been found in KATP channel genes ABCC8 and KCNJ11, but to date only twenty mutations have been identified in KCNJ11, most of them are missense mutations and only one is a single base deletion. The Fo-CHI has been demonstrated to arise in individuals who have a germline mutation in the paternal allele of ABCC8 or KCNJ11 in addition to a somatic loss of the maternally derived chromosome region 11p15 in adenomatous pancreatic beta-cells, while Di-CHI predominantly arises from the autosomal recessive inheritance of KATP channel gene mutations. Here we describe the molecular findings in nine children who presented, in the neonatal period, with signs and symptoms of hypoglycemia and diagnosed affected by CHI according to international diagnostic criteria. Direct sequencing of the complete coding exon and promoter region of KCNJ11 gene showed, in two Italian patients, two new heterozygous mutations which result in the appearance of premature translation termination codons resulting in the premature end of Kir6.2. Interestingly most of the CHI mutations detected in other population studies are situated in the ABCC8 gene.

Neonatal hyperinsulinism: clinicopathologic correlation

Neonatal hyperinsulinism is a life-threatening disease that, when treated by total pancreatectomy, leads to diabetes and pancreatic insufficiency. A more conservative approach is now possible since the separation of the disease into a nonrecurring focal form, which is cured by partial surgery, and a diffuse form, which necessitates total pancreas removal only in cases of medical treatment failure. The pathogenesis of the disease is now divided into K-channel disease (hyperinsulinemic hypoglycemia, familial [HHF] 1 and 2), which can mandate surgery, and other metabolic causes, HHF 3 to 6, which are treated medically in most patients. The diffuse form is inherited as a recessive gene on chromosome 11, whereas most cases of the focal form are caused by a sulfonylurea receptor 1 defect inherited from the father, which is associated with a loss of heterozygosity on the corresponding part of the mother's chromosome 11. The rare bifocal forms result from a maternal loss of heterozygosity specific to each focus. Paternal disomy of chromosome 11 is a rare cause of a condition similar to Beckwith-Wiedemann syndrome. A preoperative PET scan with fluorodihydroxyphenylalanine and perioperative frozen-section confirmation are the types of studies done before surgery when needed. Adult variants of the disease are less well defined at the present time.

Genotype-phenotype associations in patients with severe hyperinsulinism of infancy

In hyperinsulinism of infancy (HI), unregulated insulin secretion causes hypoglycemia. Pancreatectomy may be required in severe cases, most of which result from a defect in the beta-cell KATP channel, encoded by ABCC8 and KCNJ11. Pancreatic histology may be classified as diffuse or focal disease (the latter associated with single paternal ABCC8 mutations), indicated by the presence of islet cell nuclear enlargement in areas of diffuse abnormality. We investigated genotype-phenotype associations in a heterogeneous Australian cohort. ABCC8 and KCNJ11 genes were sequenced and case histology was reviewed in 21 infants who had pancreatectomy. Ninety-eight control DNA samples were tested by single nucleotide polymorphism analysis. Eighteen ABCC8 mutations were identified, 10 novel. Eleven patients (4 compound heterozygote, 4 single mutation, 3 no mutation detected) had diffuse hyperinsulinism. Nine patients had focal hyperinsulinism (6 single paternal mutation, 2 single mutation of undetermined parental origin, 1 none found) with absence of islet cell nuclear enlargement outside the focal area, although centroacinar cell proliferation and/or nesidiodysplasia was present in 7 cases. Regeneration after near-total pancreatectomy was documented in 4 patients, with aggregates of endocrine tissue observed at subsequent operations in 3. Although the absence of enlarged islet cell nuclei is a useful discriminant of focal hyperinsulinism associated with a paternal ABCC8 mutation, further research is needed to understand the pathophysiology of other histological abnormalities in patients with HI, which may have implications for mechanisms of ductal and islet cell proliferation. Previous surgery should be taken into account when interpreting pancreatic histology.

The Knudson's two-hit model and timing of somatic mutation may account for the phenotypic diversity of focal congenital hyperinsulinism

BACKGROUND

Congenital hyperinsulinism (CHI) is associated with focal hyperplasia of endocrine tissue in 40-65% of patients. Focal CHI is sporadic and is caused by a germline, paternally inherited, mutation of the SUR1 (ABCC8) or KIR6.2 (KCNJ11) genes (encoding subunits of the pancreatic ATP-dependent potassium channel) together with somatic maternal haploinsufficiency for 11p15.5. Plurifocal or large forms of focal CHI are a cause of apparent failure of surgery, and their underlying mechanism has not been thoroughly investigated.

PATIENTS

We here report two patients with bifocal CHI as evidenced by relapsing hypoglycemia after removal of the first focal lesion and the detection of a second, distinct, focal adenomatous hyperplasia during later surgery (patients 1 and 2) and a patient with a giant focal lesion involving the major part of the pancreas (patient 3).

RESULTS

In the three patients, a germline, paternally inherited, mutation of SUR1 was found. In patients 1 and 2, haploinsufficiency for the maternal 11p15.5 region resulted from a somatic deletion specific for each of the focal lesions, as shown by the diversity of deletion break points. In patient 3, an identical somatic maternal 11p15 deletion demonstrated by similar break points was shown in two independent lesion samples, suggesting a very early event during pancreas embryogenesis.

CONCLUSION

Individual patients with focal hyperinsulinism may have more than one focal pancreatic lesion due to separate somatic maternal deletion of the 11p15 region. These patients and those with solitary focal lesions may follow the two-hit model described by Knudson. The stage of embryogenesis at which the somatic event occurs may account for the observed histological diversity (early event giant lesion, later event small lesion).

[Congenital hyperinsulinism in newborn and infant]

Congenital hyperinsulinism (HI) is the most important cause of hypoglycaemia in early infancy. The inappropriate oversecretion of insulin is responsible for profound hypoglycaemias requiring aggressive treatment to prevent severe and irreversible brain damage. Several classifications of HI can be attempted, based on: 1) the onset of hypoglycemia in the neonatal period or later in infancy; 2) the histological lesion: focal or diffuse; 3) the genetic transmission: sporadic, recessive, or less frequently dominant. The most common underlying mechanism of HI is dysfunction of the pancreatic ATP-sensitive potassium channel (K(+)(ATP)). The 2 subunits of the K(+)(ATP) channel are encoded by either the sulfonylurea receptor gene (SUR1 or ABCC8) or the inward-rectifying potassium channel gene (KIR6.2. or KCNJ11), both located in the 11p15.1 region. Focal CHI has been shown to result from a paternally inherited mutation on the SUR1 or KIR6.2 gene and loss of the maternal 11p15 allele restricted to the pancreatic lesion. Diffuse HI, frequently due to mutations of the SUR1 or KIR6.2 genes of autosomal recessive inheritance is genetically heterogeneous. The distinction between the focal and the diffuse HI is very important, because the treatments are different. To distinguish between focal and diffuse HI, transhepatic catheterisation with pancreatic venous sampling was the reference technique, but will likely be replaced by [(18)F] Fluoro-L-Dopa PET scan, which is easier to perform. In absence of response to the medical treatment (diazoxide) a limited pancreatectomy permits to cure focal HI, while a diffuse HI requires a subtotal pancreatectomy with high risk of subsequent diabetes mellitus.

Multidisciplinary management of surgical disorders of the pancreas in childhood

OBJECTIVES

To describe the frequency and range of pancreatic disorders in children requiring surgical intervention and to highlight the importance of multidisciplinary management.

METHODS

An audit of all children under 17 years of age referred with surgical disorders of the pancreas or pancreatitis to a regional pediatric gastroenterology unit in the United Kingdom during a 10-year period. A retrospective chart review of clinical features, pathology and outcome was undertaken.

RESULTS

Surgical intervention was required for the following pancreatic disorders: persistent hyperinsulinemic hypoglycemia of infancy (n = 4), pancreatic tumors (n = 5), pancreaticobiliary malunion (n = 12), pancreatic trauma (n = 6) and pancreatitis (n = 10). The indications for surgery in acute pancreatitis were a persistent pseudocyst (n = 1) and treatment of an underlying cause of pancreatitis (n = 4); in chronic pancreatitis, surgery was used to treat symptomatic pancreatic duct strictures (n = 4). One child died of a progressive lymphoma but all others who underwent surgery are alive and well. All 33 children with acute pancreatitis, including four with pancreatic necrosis, survived.

CONCLUSIONS

Surgery for pancreatic disorders in children is rarely required but may be necessary a) for definitive management of primary pancreatic pathology, b) to treat sequelae of acute or chronic pancreatitis and c) to treat an underlying cause of pancreatitis. There is a broad spectrum of potential pathologies. These patients are best managed by a multidisciplinary team approach.

Hyperinsulinisme persistant du nouveau-né et du nourrisson : traitement chirurgical des lésions pancréatiques focales dans 60 cas

Congenital hyperinsulinism of infancy is a severe disease that leads to important brain damage. Two different forms of the disease have been identified by pathologists: a diffuse and a focal form. A specific genetic anomaly identified in focal forms has never been described in diffuse ones. However, for most of authors, failure of medical treatment results in near-total pancreatectomy in all cases, which ends in diabetus. The aim of this retrospective study was to assess the results of elective partial pancreatectomy performed in 60 cases of focal form of hyperinsulinism over the last 18 years. Fifty-eight patients were cured with euglycemia at both fasting and hyperglycaemic tests without insulin-dependent diabetes mellitus. One patient is still in hypoglycaemia from unrecognized lesion; insulin-dependent diabetes mellitus occurred in one case nine years after surgery (a near-total pancreatectomy has been performed because of unknown focal form, in 1985).

Growth restriction and exendin 4 promote endocrine expression in cultured islet cells derived from patients with persistent hyperinsulinemic hypoglycemia of infancy (PHHI)

Islets derived from patients with persistent hyperinsulinemic hypoglycemia of infancy, PHHI, show a significant capacity to proliferate in vitro without the addition of growth factors. However, as with other differentiated cells, PHHI-derived islet cells show a loss of differentiated function with repeated subculture. Here, we have investigated methods of extending the differentiated function of PHHI-derived endocrine cells following in vitro expansion. The experiments were carried out on 13 primary pancreatic cell cultures from patients with PHHI, the majority of which (n = 11) were glucose unresponsive--a distinctive feature of PHHI disease. After a 20-day period of cell expansion in 10% FCS, cells were switched to media containing varying concentrations of FCS with or without exendin 4 and endocrine function was measured using ELISA and RT-PCR for insulin and PDX-1. Switching the expanded cultures to low serum was shown to slow cell division while maintaining the residual differentiated endocrine characteristics of all the cultures tested. Exendin 4 was shown to further enhance the improved insulin secretion shown by low serum cultures, although in glucose nonresponsive cells, this was at the expense of insulin stores. However, we did observe that exendin 4 could upregulate insulin secretion, insulin storage, and PDX-1 expression in glucose responsive PHHI cultures.

Laparoscopic diagnosis and cure of hyperinsulinism in two cases of focal adenomatous hyperplasia in infancy

Persistent hyperinsulinemic hypoglycemia of infancy or congenital hyperinsulinism of the neonate is a rare condition that may cause severe neurologic damage if the disease is unrecognized or inadequately treated. Current treatment aims to restore normal blood glucose levels by providing a carbohydrate-enriched diet and drugs that inhibit insulin secretion. If medical treatment fails, then surgery is required. Because congenital hyperinsulinism may be caused either by diffuse involvement of pancreatic beta-cells or by a focal cluster of abnormal beta-cells, the extent of pancreatectomy varies. We report on 2 patients with a focal form of the disease for whom diagnosis was made with laparoscopy. Laparoscopic enucleation of the lesion was curative.

The surgical management of congenital hyperinsulinemic hypoglycemia in infancy

BACKGROUND

Congenital hyperinsulinism (CHI) is characterized by profound hypoglycaemia caused by inappropriate insulin secretion. CHI is a heterogeneous disorder with at least 2 histologic lesions and several implicated genes. If CHI is caused by a focal lesion, elective surgery is the only treatment because it leads to complete recovery without diabetes; on the contrary, diffuse CHI can only be cured by near-total pancreatectomy, and medical treatment, if efficient, is preferable. It is therefore mandatory to distinguish the 2 forms of CHI, and the surgeon has to fullfill his role in the multidisciplinary team that deals with CHI.

METHODS

A total of 134 patients with CHI were investigated both radiologically and with molecular biology. Pathology was the only proof of focal or diffuse lesions, and the pancreatic tissue could be studied by electrophysiology (Katp and Ca channels) and gene study.

RESULTS

In 59 infants with CHI, a focal lesion was suspected by radiology and proved by extemporaneous pathology; partial pancreatectomy (33 tail +/- body, 19 head, 5 isthmus resections) was performed, and molecular biology and histochemistry confirmed the genetic lesion specific to the focal disease; 75 near-total pancreatectomies were necessary in diffuse disease to prevent brain damage.

CONCLUSIONS

CHI is a severe brain-threatening disease. Surgery is indicated in all focal diseases, providing they are diagnosed preoperatively. In diffuse disease with resistance to medical treatment, near-total pancreatectomy is a last resort option that hopefully will be improved in the future with culture of beta cells and genetic modification of the beta cell disease before autograft.

A multidisciplinary approach to the focal form of congenital hyperinsulinism leads to successful treatment by partial pancreatectomy

BACKGROUND/PURPOSE

Congenital hyperinsulinism (HI) causes severe hypoglycemia in neonates and infants. Recessive mutations of the beta-cell K(ATP) channel genes cause diffuse HI, whereas loss of heterozygosity together with inheritance of a paternal mutation cause focal adenomatous HI. Although these 2 forms of HI are clinically identical, focal HI can be cured surgically. The authors reviewed their experience with partial pancreatectomy for focal HI.

METHODS

From December 1998 to January 2003, 38 patients (ages 2 weeks to 14 months; median age, 10 weeks) were treated with partial pancreatectomy for focal HI. Before surgery, patients had localization studies using selective arterial calcium stimulation with venous sampling or transhepatic portal venous sampling. At operation, the focal lesion was found using the preoperative localization data and multiple pancreatic biopsies with frozen section analysis, followed by partial pancreatectomy. A complete response at follow-up was defined as no requirement for glycemic medications, no continuous tube feedings, and no diabetes mellitus.

RESULTS

Nineteen pancreatic focal lesions were in the head; 15 were in the neck, body, or tail; and 4 had more extensive involvement. Lesions that required substantial resection of the pancreatic head underwent Roux-en-Y pancreaticojejunostomy to preserve the normal body and tail. Lesions of the body or tail were usually treated with partial distal pancreatectomy. Ninety-two percent (35 of 38) of patients had a complete response to surgery. Three patients have required glycemic medications. No patient is diabetic. Surgical complications included additional resection for residual disease (3), small bowel obstruction requiring laparotomy and enterolysis (2), and chylous ascites (3) that resolved with medical management.

CONCLUSIONS

A multidisciplinary approach to patients with the focal form of congenital hyperinsulinism can distinguish focal from diffuse disease, localize focal lesions, and permit partial pancreatectomy with cure in most patients.

Preoperative evaluation of infants with focal or diffuse congenital hyperinsulinism by intravenous acute insulin response tests and selective pancreatic arterial calcium stimulation

Infants with congenital hyperinsulinism often require pancreatectomy. Recessive mutations of the ATP-dependent plasma membrane potassium channel (K(ATP)) genes, SUR1 and K(ir)6.2, cause diffuse hyperinsulinism. K(ATP) channel mutations can also cause focal disease through loss of heterozygosity for maternal 11p, resulting in expression of a paternal mutation. This study evaluated whether focal vs. diffuse hyperinsulinism could be diagnosed by acute insulin response (AIR) tests and whether arterial calcium stimulation/venous sampling (ASVS) could localize focal lesions. Fifty infants with diazoxide-unresponsive hyperinsulinism were studied. Focal lesions occurred in 70% of the cases. Positive AIR calcium occurred in 17 of 30 focal and 10 of 13 diffuse cases (P < 0.04). Positive AIR tolbutamide occurred in 27 of 30 focal vs. seven of 13 diffuse cases (P < 0.02); K(ATP) channel mutations were identified in four of the latter. ASVS localized the lesion in 24 of 33 focal cases (73%) but correctly diagnosed diffuse disease in only four of 13 cases. These results indicate that preoperative AIR tests do not distinguish focal vs. diffuse disease because some K(ATP) channel mutations retain responsiveness to tolbutamide. The ASVS test can be used to localize focal lesions in infants. The combination of ASVS, careful intraoperative histologic analysis, and surgical expertise succeeded in correcting hypoglycemia in 86% of the infants with focal hyperinsulinism.

Genetics of congenital hyperinsulinism

Congenital hyperinsulinism (CHI) is a clinically and genetically heterogeneous entity and causes severe hypoglycemia in neonates and infants. The clinical heterogeneity is manifested by severity ranging from extremely severe, life-threatening disease to very mild clinical symptoms, which may even be difficult to identify. Furthermore, clinical responsiveness to medical and surgical management is extremely variable. Recent discoveries have begun to clarify the molecular etiology of this disease in about 50% of cases. Mutations in five different genes have been identified in patients with this clinical syndrome. Most cases are caused by mutations in the genes ABCC8 and KCNJ11 coding for either of the two subunits of the beta-cell KATP channel (SUR1 and Kir6.2). Recessive mutations of the beta-cell K(ATP) channel genes cause diffuse HI, whereas loss of heterozygosity together with inheritance of a paternal mutation causes focal adenomatous HI. In other cases, CHI is caused by mutations in genes coding for the beta-cell enzymes glucokinase (GK), glutamate dehydrogenase (GDH), and SCHAD. However, for as many as 50% of the cases, no genetic etiology has yet been determined. The study of the genetics of this disease has provided important new information regarding beta-cell physiology.

Focal and diffuse forms of congenital hyperinsulinism: the keys for differential diagnosis

Congenital hyperinsulinism is clinically characterized by an inappropriate insulin secretion resulting in recurrent severe hypoglycemia. Nesidioblastosis, the proliferation of islets cells budding off from pancreatic ducts, has been considered for years as the histological lesion responsible for the syndrome. In our morphological studies, we demonstrated that nesidioblastosis is not specific for the disease, which is actually not a single entity. Indeed, we recognized the existence of two different forms--a diffuse form and a focal form--and demonstrated that they can be differentiated on the basis of morphological criteria, even on frozen sections during surgery. This histological distinction directs the therapeutic approach because the patients suffering from the focal form of the syndrome can be completely cured by a very limited pancreatectomy. Molecular findings confirmed the reliability of this histological distinction, showing a specific genetic background for each form.