Congenital Hyperinsulinism Research Articles

The combination of next generation sequencing and technological devices allows a precision medicine approach in congenital hyperinsulinism: the case of a pregnant mother and the child she gave birth.

The combination of next generation sequencing and technological devices allows a precision medicine approach in congenital hyperinsulinism: the case of a pregnant mother and the child she gave birth.

Low-level mosaic GCK mutations in children with diazoxide-unresponsive congenital hyperinsulinism.

Some children with diazoxide-unresponsive congenital hyperinsulinism (HI) lack any detectable disease-causing mutation in peripheral blood DNA. To examine whether somatic post-zygotic mutations of known HI genes are responsible for disease in children with diazoxide-unresponsive HI requiring surgery with histology not classified as focal or Localized Islet Nuclear Enlargement (LINE), and without detectable mutations by standard genetic testing of peripheral blood DNA. Next-generation sequencing (NGS) was performed on specimens of pancreas from 10 children with diazoxide-unresponsive HI. Four unique GCK mutations were identified at low levels of mosaicism ranging from 4.4-10.1% in pancreatic DNA from five of these 10 children. The GCK mutations were not detectable in peripheral blood DNA by NGS in three cases from which peripheral blood DNA was available for testing. All four GCK mutations have been previously published as activating HI mutations. The histology was consistent with diffuse-HI in four of the five cases with mosaic GCK mutations. In one of these, hypomethylation of IC2 on chromosome 11p was identified in pancreatic and peripheral blood DNA. Histology of the fifth case revealed minor islet abnormalities suggestive of Beckwith Wiedemann Spectrum (BWSp) although molecular analysis for 11pUPD was negative in pancreas. These results indicate that post-zygotic somatic GCK mutations are responsible for some cases of non-focal diazoxide-unresponsive hyperinsulinism.

8721 A Case of Congenital Hyperinsulinism Manifesting as Transient Hypoglycemia During Illness Due to Mosaic Variant of Unknown Significance in ABCC8

Abstract Disclosure: E.E. Bell-Sambataro: None. L. Mamilly: None. Background: Congenital hyperinsulinism (CHI) is characterized by inappropriate secretion of insulin during periods of low blood glucose. CHI can lead to significant complications such as seizures, developmental delays and neurologic damage. CHI can be caused by multiple genetic variants. The most common genetic etiologies are loss of function mutations in the genes ABCC8 and KCNJ11 encoding the pancreatic Beta (β)-cell ATP-sensitive potassium channel causing over secretion of insulin from the β-cells. We report a challenging pediatric case with a clinical presentation of CHI in an infant with a de novo mosaic ABCC8 gene variant of unknown significance manifesting only during times of illness. Clinical Case: A male infant born at 36 weeks gestational age was transferred to a tertiary center NICU secondary to seizure activity and hypoglycemia after the 24 hours of life with glucose levels as low as 32 mg/dL. His birth weight was normal and there was not maternal history of diabetes mellitus. The hypoglycemia persisted throughout the first week of life and required a glucose infusion rate of 11 mg/kg/min, without success in obtaining a critical sample. He had multiple seizures and MRI brain showed signs of hypoglycemic encephalopathy. Subsequently, he was weaned off IV dextrose and completed a 6 hour safety fast prior to discharge. Rapid genome testing resulted in a de novo, mosaic variant of unknown significance in ABCC8 (C.3622G>A resulting in amino acid substitution p.Glu1208Lys). His family reported significant but transient hypoglycemia during times of illness. At the age of 11 months, he was hospitalized for significant hypoglycemia during an episode of acute gastroenteritis and was treated with dextrose-containing fluids for 36 hours. A subsequent diagnostic fasting study resulted in hypoglycemia within 5.5 hours with capillary glucose of 49 mg/dL. At the time of hypoglycemia, beta hydroxybutyrate was inappropriately low at 0.78 mm, insulin level was suppressed <2 mcIU/mL. Glucagon (30 mcg/Kg) was administered after the initial sample was drawn with a significant increase in glucose from 49 mg/dL to 103 mg/dL. Based on the positive glucagon response and low serum ketone, the clinical diagnosis of CHI was made and diazoxide was initiated while awaiting other results. After the second dose of diazoxide, all glucose levels remained above 80 mg/dL. He was sent home on a continuous glucose monitor and diazoxide. Conclusion: CHI can occur due to autosomal recessive or autosomal dominant ABCC8 loss-of-function mutations of which more than half are not responsive to diazoxide. In this case report, we describe the diagnosis of hyperinsulinemic hypoglycemia in an infant with an ABCC8 variant classified with unknown significance. We describe a good initial response to diazoxide in normalizing blood glucose levels in this infant. Presentation: 6/2/2024

7354 A Case of Continuous Glucose Monitoring in Children with Glutamate Dehydrogenase Hyperinsulinism

Abstract Disclosure: K. Kim: None. E. Mun: None. C. Jung Eun: None. R. Lee: None. K. Hae Soon: None. A Case of Continuous Glucose Monitoring in Children with Glutamate Dehydrogenase(GLUD1) Hyperinsulinism Background: Continuous glucose monitoring (CGM) is increasingly being used in pediatric patients with diabetes. CGM can help prevent hypoglycemia and support the management of hypoglycemic problems. Congenital hyperinsulinism is a rare condition in which hypoglycemia occurs due to hyperinsulinemia caused by the dysregulation of insulin secretion, and it can lead to complications such as developmental delay and seizures. Case presentation: A 14 months years old, male infant was referred to the pediatric emergency room representing symptoms of GTC type seizure during 2-3 minutes and hypoglycemia. He had no perinatal problems with no significant family history. During seizure, He was found to have a blood glucose of 39mg/dL, ammonia of 183μmol/L, insulin of 28.3 mcg/mL and ketone 203.4μmol/L. C-peptide was 1.4 ng/mL (≥ 0.5ng/mL) and free fatty acid was 0.492mmol/L (<1.7mmol/L) for evaluation. He was thought to have GDH hyperinsulinism. Blood glucose level was followed up with feeding frequency and protein restricted diet. Congenital hyperinsulinism genetic test was requested. Brain CT showed normal. EEG revealed no focal abnormalities, no persistent asymmetries. CGM was used in patient. Diazoxide was started with 5mg/kg/day in 2 divided doses and then blood glucose level was observed below 60mg/dL 3-4 times for day. Complete blood counts and uric acid levels were measured at baseline and 5 days after starting diazoxide therapy, and thereafter increase to 6.25mg/kg/day Conclusions: In children with GDH hyperinsulinism, the utilization of CGM can serve as a tool to assess the impact of treatment before and after medication therapy, as well as also aiding in hypoglycemia prevention. Presentation: 6/2/2024

6799 RZ358 Therapy. A Novel Approach to Hyperinsulinemia in Metastatic Neuroendocrine Tumor Patients

Abstract Disclosure: J. Noreña: None. T. Akcan: None. S. Patel: None. W. Madeleine: None. S. Shaheen: None. M. Tan: None. RZ358, an intravenously administered monoclonal antibody, targets a unique allosteric site on the insulin receptor. It is under investigation for hypoglycemia due to congenital hyperinsulinism. We present a case of its efficacy in treating refractory hyperinsulinemic-hypoglycemia (HH) due to a metastatic pancreatic neuroendocrine tumor (pNET). Clinical Case: A 50-year-old woman with a 6-year history of HH initially presented in 2016 with epigastric pain and was diagnosed with gastrin secreting pNET pT3N1. After Whipple surgery and cholecystectomy. A well-differentiated, WHO grade 2 NET, positive in immunohistochemistry for AE1/3, synaptophysin and Ki-67 index of 9.2% was confirmed. She presented recurrent disease with liver metastasis requiring somatostatin analogue Lanreotide. Subsequently despite Lanreotide, hypoglycemia persisted, and 72-hour fast confirmed HH. DOTATATE scan showed progression to new liver lesions. Everolimus was started and subsequently peptide receptor radionuclide therapy (PRRT) with fair hypoglycemia control. Unfortunately, her disease progressed. Oral glucose, cornstarch, and diazoxide failed. After a left hepatectomy and transarterial chemoembolization, her severe hypoglycemia improved briefly. Despite high-dose dexamethasone (up to 4 mg daily), octreotide 400 mcg every 8 hours, and high-calorie total parenteral nutrition (TPN) (over 800 grams of carbohydrates daily), she required multiple hospitalizations for persistent symptomatic hypoglycemia. Moreover, these therapies led to significant side effects, including recurrent episodes of volume overload, 240 pounds weight gain over a year, and Cushingoid features. Given RZ358's reports in reversing HH in rodents, humans, and a recent report of successful use in a malignant insulinoma case, we aimed to start RZ358 in our patient. We obtained, emergency use authorization from the FDA, IRB of Stanford University School of Medicine approval, and patient written informed consent. RZ358 was started at 6 mg/kg biweekly, along with octreotide, dexamethasone, and TPN. RZ358 dosage was later increased to 9 mg/kg weekly, allowing a substantial reduction in dexamethasone to physiological doses and a 50% reduction in TPN carbohydrate requirements. She achieved normoglycemia and returned home, but missing a single weekly RZ358 dose caused recurrent severe hypoglycemia until the next dose administration.As her disease progressed, the patient opted for comfort care, discontinuing TPN and RZ358. Conclusion: RZ358 represents a novel and unique treatment option for refractory HH in patients with metastatic NETs and can improve clinical outcomes when standard interventions fail. This case underscores the potential of RZ358, a monoclonal antibody, to treat HH beyond its approved use for congenital cases, suggesting its applicability to cases of hyperinsulinemia secondary to NETs in adults. Presentation: 6/2/2024

9286 RZ358 Therapy. A Novel Approach To Hyperinsulinemia In Metastatic Neuroendocrine Tumor Patients

Abstract Disclosure: J. Noreña: None. T. Akcan: None. S. Patel: None. M. Welsh: None. S. Shaheen: None. M. Tan: None. RZ358, an intravenously administered monoclonal antibody, targets a unique allosteric site on the insulin receptor. It is under investigation for hypoglycemia due to congenital hyperinsulinism. We present a case of its efficacy in treating refractory hyperinsulinemic-hypoglycemia (HH) due to a metastatic pancreatic neuroendocrine tumor (pNET). Clinical Case: A 50-year-old woman with a 6-year history of HH initially presented in 2016 with epigastric pain and was diagnosed with gastrin secreting pNET pT3N1. After Whipple surgery and cholecystectomy. A well-differentiated, WHO grade 2 NET, positive in immunohistochemistry for AE1/3, synaptophysin and Ki-67 index of 9.2% was confirmed. She presented recurrent disease with liver metastasis requiring somatostatin analogue Lanreotide. Subsequently despite Lanreotide, hypoglycemia persisted, and 72-hour fast confirmed HH. DOTATATE scan showed progression to new liver lesions. Everolimus was started and subsequently peptide receptor radionuclide therapy (PRRT) with fair hypoglycemia control. Unfortunately, her disease progressed. Oral glucose, cornstarch, and diazoxide failed. After a left hepatectomy and transarterial chemoembolization, her severe hypoglycemia improved briefly. Despite high-dose dexamethasone (up to 4 mg daily), octreotide 400 mcg every 8 hours, and high-calorie total parenteral nutrition (TPN) (over 800 grams of carbohydrates daily), she required multiple hospitalizations for persistent symptomatic hypoglycemia. Moreover, these therapies led to significant side effects, including recurrent episodes of volume overload, 240 pounds weight gain over a year, and Cushingoid features. Given RZ358's reports in reversing HH in rodents, humans, and a recent report of successful use in a malignant insulinoma case, we aimed to start RZ358 in our patient. We obtained, emergency use authorization from the FDA, IRB of Stanford University School of Medicine approval, and patient written informed consent. RZ358 was started at 6 mg/kg biweekly, along with octreotide, dexamethasone, and TPN. RZ358 dosage was later increased to 9 mg/kg weekly, allowing a substantial reduction in dexamethasone to physiological doses and a 50% reduction in TPN carbohydrate requirements. She achieved normoglycemia and returned home, but missing a single weekly RZ358 dose caused recurrent severe hypoglycemia until the next dose administration.As her disease progressed, the patient opted for comfort care, discontinuing TPN and RZ358. Conclusion: RZ358 represents a novel and unique treatment option for refractory HH in patients with metastatic NETs and can improve clinical outcomes when standard interventions fail. This case underscores the potential of RZ358, a monoclonal antibody, to treat HH beyond its approved use for congenital cases, suggesting its applicability to cases of hyperinsulinemia secondary to NETs in adults. Presentation: 6/2/2024

6799 RZ358 Therapy. A Novel Approach To Hyperinsulinemia In Metastatic Neuroendocrine Tumor Patients

Abstract Disclosure: J. Noreña: None. T. Akcan: None. S. Patel: None. W. Madeleine: None. S. Shaheen: None. M. Tan: None. RZ358, an intravenously administered monoclonal antibody, targets a unique allosteric site on the insulin receptor. It is under investigation for hypoglycemia due to congenital hyperinsulinism. We present a case of its efficacy in treating refractory hyperinsulinemic-hypoglycemia (HH) due to a metastatic pancreatic neuroendocrine tumor (pNET). Clinical Case: A 50-year-old woman with a 6-year history of HH initially presented in 2016 with epigastric pain and was diagnosed with gastrin secreting pNET pT3N1. After Whipple surgery and cholecystectomy. A well-differentiated, WHO grade 2 NET, positive in immunohistochemistry for AE1/3, synaptophysin and Ki-67 index of 9.2% was confirmed. She presented recurrent disease with liver metastasis requiring somatostatin analogue Lanreotide. Subsequently despite Lanreotide, hypoglycemia persisted, and 72-hour fast confirmed HH. DOTATATE scan showed progression to new liver lesions. Everolimus was started and subsequently peptide receptor radionuclide therapy (PRRT) with fair hypoglycemia control. Unfortunately, her disease progressed. Oral glucose, cornstarch, and diazoxide failed. After a left hepatectomy and transarterial chemoembolization, her severe hypoglycemia improved briefly. Despite high-dose dexamethasone (up to 4 mg daily), octreotide 400 mcg every 8 hours, and high-calorie total parenteral nutrition (TPN) (over 800 grams of carbohydrates daily), she required multiple hospitalizations for persistent symptomatic hypoglycemia. Moreover, these therapies led to significant side effects, including recurrent episodes of volume overload, 240 pounds weight gain over a year, and Cushingoid features. Given RZ358's reports in reversing HH in rodents, humans, and a recent report of successful use in a malignant insulinoma case, we aimed to start RZ358 in our patient. We obtained, emergency use authorization from the FDA, IRB of Stanford University School of Medicine approval, and patient written informed consent. RZ358 was started at 6 mg/kg biweekly, along with octreotide, dexamethasone, and TPN. RZ358 dosage was later increased to 9 mg/kg weekly, allowing a substantial reduction in dexamethasone to physiological doses and a 50% reduction in TPN carbohydrate requirements. She achieved normoglycemia and returned home, but missing a single weekly RZ358 dose caused recurrent severe hypoglycemia until the next dose administration.As her disease progressed, the patient opted for comfort care, discontinuing TPN and RZ358. Conclusion: RZ358 represents a novel and unique treatment option for refractory HH in patients with metastatic NETs and can improve clinical outcomes when standard interventions fail. This case underscores the potential of RZ358, a monoclonal antibody, to treat HH beyond its approved use for congenital cases, suggesting its applicability to cases of hyperinsulinemia secondary to NETs in adults. Presentation: 6/2/2024

9286 RZ358 Therapy. A Novel Approach to Hyperinsulinemia in Metastatic Neuroendocrine Tumor Patients

Abstract Disclosure: J. Noreña: None. T. Akcan: None. S. Patel: None. M. Welsh: None. S. Shaheen: None. M. Tan: None. RZ358, an intravenously administered monoclonal antibody, targets a unique allosteric site on the insulin receptor. It is under investigation for hypoglycemia due to congenital hyperinsulinism. We present a case of its efficacy in treating refractory hyperinsulinemic-hypoglycemia (HH) due to a metastatic pancreatic neuroendocrine tumor (pNET). Clinical Case: A 50-year-old woman with a 6-year history of HH initially presented in 2016 with epigastric pain and was diagnosed with gastrin secreting pNET pT3N1. After Whipple surgery and cholecystectomy. A well-differentiated, WHO grade 2 NET, positive in immunohistochemistry for AE1/3, synaptophysin and Ki-67 index of 9.2% was confirmed. She presented recurrent disease with liver metastasis requiring somatostatin analogue Lanreotide. Subsequently despite Lanreotide, hypoglycemia persisted, and 72-hour fast confirmed HH. DOTATATE scan showed progression to new liver lesions. Everolimus was started and subsequently peptide receptor radionuclide therapy (PRRT) with fair hypoglycemia control. Unfortunately, her disease progressed. Oral glucose, cornstarch, and diazoxide failed. After a left hepatectomy and transarterial chemoembolization, her severe hypoglycemia improved briefly. Despite high-dose dexamethasone (up to 4 mg daily), octreotide 400 mcg every 8 hours, and high-calorie total parenteral nutrition (TPN) (over 800 grams of carbohydrates daily), she required multiple hospitalizations for persistent symptomatic hypoglycemia. Moreover, these therapies led to significant side effects, including recurrent episodes of volume overload, 240 pounds weight gain over a year, and Cushingoid features. Given RZ358's reports in reversing HH in rodents, humans, and a recent report of successful use in a malignant insulinoma case, we aimed to start RZ358 in our patient. We obtained, emergency use authorization from the FDA, IRB of Stanford University School of Medicine approval, and patient written informed consent. RZ358 was started at 6 mg/kg biweekly, along with octreotide, dexamethasone, and TPN. RZ358 dosage was later increased to 9 mg/kg weekly, allowing a substantial reduction in dexamethasone to physiological doses and a 50% reduction in TPN carbohydrate requirements. She achieved normoglycemia and returned home, but missing a single weekly RZ358 dose caused recurrent severe hypoglycemia until the next dose administration.As her disease progressed, the patient opted for comfort care, discontinuing TPN and RZ358. Conclusion: RZ358 represents a novel and unique treatment option for refractory HH in patients with metastatic NETs and can improve clinical outcomes when standard interventions fail. This case underscores the potential of RZ358, a monoclonal antibody, to treat HH beyond its approved use for congenital cases, suggesting its applicability to cases of hyperinsulinemia secondary to NETs in adults. Presentation: 6/2/2024

Biomarkers and Diagnostic Thresholds for Congenital Hyperinsulinism.

Congenital Hyperinsulinism (CHI) is associated with inappropriately high levels of C-peptide in the context of hypoglycemia. We aimed to better clarify a diagnostic threshold value of C-peptide for children presenting with CHI. This was a retrospective case-control analysis, examining all hypoglycemia screens, undertaken between 2009 and 2019 at a quaternary paediatrics unit. Plasma C-peptide, insulin, free fatty acid (FFA) and B-hydroxybutyrate (BHOB) concentrations in children diagnosed with CHI were compared with concentrations in children diagnosed with other conditions. All patients requiring hypoglycaemic screens at the quaternary children's hospital were analysed. Median [C-peptide] were statistically significantly different between CHI (147) and non-CHI (72) patients, p < 0.05. The Youden Index indicated that a [C-peptide] value of 291.5 pmol/L would give the greatest optimization of sensitivity (82%) and specificity (99%) for detecting CHI. Median [insulin] differed significantly between the cohorts with a level of 64 pmol/L for CHI patients compared with 0 pmol/L with non-CHI patients (p < 0.01). Median [BOHB] was 0 μmol/L in CHI patients as compared with 2378 μmol/L for non-CHI patients (p < 0.01). Median [FFA] levels were 1910 μmol/L in the non-CHI cohort, compared with 0 in the CHI cohort (p < 0.01). This study suggests that a C-peptide concentration greater than 291.5 pmol/L is diagnostic of CHI in children. C-peptide appears to offer the greatest utility as a biochemical diagnostic test for CHI and could be prioritised for laboratory analysis.

Safety of lanreotide in infants with congenital hyperinsulinism

Safety of lanreotide in infants with congenital hyperinsulinism

Management strategies and patient outcomes of congenital hyperinsulinism (CHI) related with beckwith-wiedemann syndrome (BWS) - insights from an CHI highly specialized centre

Management strategies and patient outcomes of congenital hyperinsulinism (CHI) related with beckwith-wiedemann syndrome (BWS) - insights from an CHI highly specialized centre

Neonatal hyperinsulinism: a retrospective study of presentation and management in a tertiary neonatal intensive care unit in the UK

ObjectiveReports of hyperinsulinism typically focus on infants managed by highly specialised services. However, neonates with hyperinsulinism are initially managed by neonatologists and often not referred to specialists. This study aimed...

AI-Based Discovery and CryoEM Structural Elucidation of a KATP Channel Pharmacochaperone.

Pancreatic KATP channel trafficking defects underlie congenital hyperinsulinism (CHI) cases unresponsive to the KATP channel opener diazoxide, the mainstay medical therapy for CHI. Current clinically used KATP channel inhibitors have been shown to act as pharmacochaperones and restore surface expression of trafficking mutants; however, their therapeutic utility for KATP trafficking impaired CHI is hindered by high-affinity binding, which limits functional recovery of rescued channels. Recent structural studies of KATP channels employing cryo-electron microscopy (cryoEM) have revealed a promiscuous pocket where several known KATP pharmacochaperones bind. The structural knowledge provides a framework for discovering KATP channel pharmacochaperones with desired reversible inhibitory effects to permit functional recovery of rescued channels. Using an AI-based virtual screening technology AtomNet® followed by functional validation, we identified a novel compound, termed Aekatperone, which exhibits chaperoning effects on KATP channel trafficking mutations. Aekatperone reversibly inhibits KATP channel activity with a half-maximal inhibitory concentration (IC50) ~ 9 μM. Mutant channels rescued to the cell surface by Aekatperone showed functional recovery upon washout of the compound. CryoEM structure of KATP bound to Aekatperone revealed distinct binding features compared to known high affinity inhibitor pharmacochaperones. Our findings unveil a KATP pharmacochaperone enabling functional recovery of rescued channels as a promising therapeutic for CHI caused by KATP trafficking defects.

A Focal Form of Diazoxide-Resistant Congenital Hyperinsulinism with Good Response to Long-Acting Somatostatin

A four-year-old female who was born term via spontaneous vaginal delivery with a birth weight of 3.4 kg had an onset of persistent hypoglycaemia at the 6th hour of life. She was diagnosed with congenital hyperinsulinism based on high glucose load, negative ketone and a good response to glucagon. Genetic workup revealed the presence of ATP Binding Cassette Subfamily C Member 8 (ABCC8 genes) mutation which indicated a focal form of congenital hyperinsulinism. She was resistant to the standard dose of oral diazoxide but responded to subcutaneous somatostatin. At the age of 3 years and 6 months, multiple daily injections of somatostatin were replaced with a long-acting monthly somatostatin analogue. With the present treatment, she had better glycaemic control, normal growth and was able to stop tube feeding.

Congenital hyperinsulinism and novel KDM6A duplications -resolving pathogenicity with genome and epigenetic analyses.

Hyperinsulinemic hypoglycemia (HI) can be the presenting feature of Kabuki syndrome (KS), which is caused by loss-of-function variants in KMT2D or KDM6A. As these genes play a critical role in maintaining methylation status in chromatin, individuals with pathogenic variants have a disease-specific epigenomic profile -an episignature. We evaluated the pathogenicity of three novel partial KDM6A duplications identified in three individuals presenting with neonatal-onset HI without typical features of KS at the time of genetic testing. Three different partial KDM6A duplications were identified by routine targeted next generation sequencing for HI and initially classified as variants of uncertain significance (VUS) as their location, and hence their impact on the gene, was not known. Whole genome sequencing (WGS) was undertaken to map the breakpoints of the duplications with DNA methylation profiling performed in two individuals to investigate the presence of a KS-specific episignature. WGS confirmed the duplication in proband 1 as pathogenic as it caused a frameshift in the normal copy of the gene leading to a premature termination codon. The duplications identified in probands 2 and 3 did not alter the reading frame and therefore their significance remained uncertain after WGS. Subsequent DNA methylation profiling identified a KS-specific episignature in proband 2 but not in proband 3. Our findings confirm a role for KDM6A partial gene duplications in the etiology of KS and highlight the importance of performing in-depth molecular genetic analysis to properly assess the clinical significance of VUS's in the KDM6A gene.

Clinical and genetic characteristics of congenital hyperinsulinism in Norway: A nationwide cohort study.

Congenital hyperinsulinism (CHI) is a rare, monogenic disease characterized by excessive insulin secretion. We aimed to evaluate all probands with suspected CHI in Norway registered over the past two decades. The study included 98 probands. Clinical data were cumulated from medical records. All probands were screened for variants in the genes ABCC8 and KCNJ11. Other CHI-related genes were Sanger-sequenced as indicated by the patients' phenotype (N=75) or analyzed by next-generation sequencing employing a panel of 30 CHI-related genes (N=23). Twenty-one probands (21%) received a diagnosis other than CHI, the most common being idiopathic ketotic hypoglycemia (9%) or syndromic hyperinsulinism (4%). In the final cohort of 77 CHI probands, genetic findings were revealed in 46 (60%). ABCC8 variants were most common (N=40) and five novel variants were identified. One proband harbored both the pathogenic GCK variant p.(Ala456Val) and the ABCC8 variant p.(Gly505Cys). Although most ABCC8 variants caused immediate disease onset with severe hypoglycemia and were diazoxide-unresponsive, eight probands had a heterozygous, apparently dominant variant with milder phenotype. Two probands had pathogenic variants in GLUD1, whereas variants in HADH, HNF4A, KCNJ11, and HK1 were identified in one proband each, the latter being non-coding. Neurologic sequelae were reported in 53% of the CHI probands. Of non-surgically treated probands, 43% had spontaneous resolution. The minimum birth prevalence of CHI in Norway is 1:19,400 live births. Individuals with disease-causing ABCC8 variants dominated our cohort. Patients with known genetic etiology had earlier and more severe disease-onset than genetically unsolved patients.

Genotype-histotype-phenotype correlations in hyperinsulinemic hypoglycemia.

Hyperinsulinemic hypoglycemia (HH) of pancreatic origin includes congenital hyperinsulinism (CHI), insulinoma, insulinomatosis, and adult-onset non-insulinoma persistent hyperinsulinemic hypoglycemia syndrome (NI-PHHS). In this review, we describe the genotype-histotype-phenotype correlations in HH and their therapeutic implications. CHI can occur from birth or later on in life. Histologically, diffuse CHI shows diffuse beta cell hypertrophy with a few giant nuclei per islet of Langerhans, most frequently caused by loss-of-function mutations in ABCC8 or KCNJ11. Focal CHI is histologically characterized by focal adenomatous hyperplasia consisting of confluent hyperplastic islets, caused by a paternal ABCC8/KCNJ11 mutation combined with paternal uniparental disomy of 11p15. CHI in Beckwith-Wiedemann syndrome is caused by mosaic changes in the imprinting region 11p15.4-11p15.5, leading to segmental or diffuse overgrowth of endocrine tissue in the pancreas. Morphological mosaicism of pancreatic islets is characterized by occurence of hyperplastic (type 1) islets in one or a few lobules and small (type 2) islets in the entire pancreas. Other rare genetic causes of CHI show less characteristic or unspecific histology. HH with a predominant adult onset includes insulinomas, which are pancreatic insulin-producing endocrine neoplasms, in some cases with metastatic potential. Insulinomas occur sporadically or as part of multiple endocrine neoplasia type 1 due to MEN1 mutations. MAFA mutations may histologically lead to insulinomatosis with insulin-producing neuroendocrine microadenomas or neuroendocrine neoplasms. NI-PHHS is mainly seen in adults and shows slight histological changes in some patients, which have been defined as major and minor criteria. The genetic cause is unknown in most cases. The diagnosis of HH, as defined by genetic, histological, and phenotypic features, has important implications for patient management and outcome.

A tale of two sisters - delayed diagnosis of genetic hyperinsulinaemic hypoglycaemia.

Congenital hyperinsulinism is the leading cause of persistent hypoglycaemia in infants and children; however, it is uncommon to be diagnosed in adulthood. We describe the cases of two sisters who presented with hyperinsulinaemic hypoglycaemia aged 47 and 57 years old, who were subsequently diagnosed with compound heterozygous likely pathogenic variants in the ABCC8 gene, a known cause of monogenic congenital hyperinsulinism. We discuss the typical presenting features, investigation findings, and treatment strategies for patients with this condition. Congenital hyperinsulinism is a rare cause of hyperinsulinaemic hypoglycaemia diagnosed in adulthood. Clinical presentation is similar to an insulinoma, and imaging modalities may assist in differentiation. There are minimal medical therapies currently available for patients non-responsive to diazoxide (such as those with ABCC8 and KCNJ11 variants). Continuous glucose monitoring can be helpful in giving patients autonomy in managing their disease, as well as relieving anxiety and fear associated with hypoglycaemia.

The Birth Prevalence of Congenital Hyperinsulinism: A Narrative Review of the Epidemiology of a Rare Disease.

Congenital hyperinsulinism (HI) is a rare pediatric disease and the most common cause of severe, persistent hypoglycemia in childhood. It is characterized by the dysregulation of insulin secretion from the pancreas and can lead to irreversible brain damage with lifelong neurodisability. The global birth prevalence of HI is currently unknown. An evidence-based estimate of HI birth prevalence is essential to improve diagnosis and patient management, to drive clinical research and the development of new treatments, and to inform public policy. In order to estimate the birth prevalence of persistent HI, a targeted literature review of studies that report HI epidemiological data was undertaken, and the strengths and limitations of each study were analyzed. Overall, eight global studies were identified that reported independently determined HI epidemiological data. The best estimate for the birth prevalence of persistent HI in European-ancestry populations is 3.5 per 100,000 births. Local consanguinity patterns appear to have a considerable impact on the birth prevalence of persistent HI in each country, precluding the application of this figure to all global populations. More epidemiological studies with robust methodology are needed to enable a reliable approximation of the incidence and prevalence of HI in global populations.

EE321 Budget Impact Model for Dasiglucagon in the Prevention and Treatment of Hypoglycemia in Pediatric Patients with Congenital Hyperinsulinism in the United States

EE321 Budget Impact Model for Dasiglucagon in the Prevention and Treatment of Hypoglycemia in Pediatric Patients with Congenital Hyperinsulinism in the United States