Congenital Hyperinsulinism International: A Community Focused on Improving the Lives of People Living With Congenital Hyperinsulinism

Congenital hyperinsulinism (HI) is a rare disease affecting newborns. HI causes severe hypoglycemia due to the overproduction of insulin. The signs and symptoms of hypoglycemia in HI babies is often not discovered until brain damage has already occurred. Prolonged hypoglycemia from HI can even lead to death. Disease management is often complex with a high burden on caregivers. Treatment options are extremely limited and often require long hospital stays to devise. Cascading from suboptimal treatments and diagnostic practices are a host of other problems and challenges that many with HI and their families experience including continued fear of hypoglycemia and feeding problems. The aim of this paper is (1) to describe the current challenges of living with HI including diagnosis and disease management told from the perspective of people who live with the condition (2), to provide family stories of life with HI, and (3) to share how a rare disease patient organization, Congenital Hyperinsulinism International (CHI) is working to improve the lives of HI patients and their families. CHI is a United States based nonprofit organization with a global focus. The paper communicates the programs the patient advocacy organization has put into place to support HI families through its virtual and in-person gatherings. The organization also helps individuals access diagnostics, medical experts, and treatments. CHI also raises awareness of HI to improve patient outcomes with information about HI and prolonged hypoglycemia in twenty-three languages. CHI drives innovation for new and better treatments by funding research pilot grants, conducting research through the HI Global Registry, and providing patient experience expertise to researchers developing new treatments. The organization is also the sponsor of the CHI Collaborative Research Network which brings medical and scientific experts together for the development of a patient-focused prioritized research agenda.

Nesidioblastosis and Insulinoma: A Rare Coexistence and a Therapeutic Challenge

Background: Nesidioblastosis and insulinoma are disorders of the endocrine pancreas causing endogenous hyperinsulinemic hypoglycemia. Their coexistence is very unusual and treatment represents a still unresolved dilemma. Case Description: The patient was a 43-year-old Caucasian woman, with a 2-year history of repeated severe hypoglycemic events. The diagnostic work-up was strongly suggestive of insulinoma and the patient was submitted to surgical treatment carried out laparoscopically under robotic assistance. However, surgical exploration and intraoperative ultrasonography failed to detect a pancreatic tumor. Resection was therefore carried out based on the results of selective intra-arterial calcium stimulation test, following a step-up approach, eventually leading to a pancreatoduodenectomy at the splenic artery. The histopathology examination and the immunohistochemical staining were consistent with adult-onset nesidioblastosis. After surgery, the patient continued to experience hypoglycemia with futile response to medical treatments (octreotide, calcium antagonists, diazoxide, and prednisone). Following multidisciplinary evaluation and critical review of a repeat abdominal computed tomography scan, a small nodular lesion was identified in the tail of the pancreas. The nodule was enucleated laparoscopically and the pathological examination revealed an insulinoma. In spite of the insulinoma resection, glycemic values were only partially restored, with residual nocturnal hypoglycemia. Administration of uncooked cornstarch (1.25 g/kg body weight) at bedtime was associated with significant improvement of interstitial glucose levels (p < 0.0001) and reduction of nocturnal hypoglycemia episodes (p = 0.0002). Conclusions: This report describes a rare coexistence of adult-onset nesidioblastosis and insulinoma, suggesting the existence of a wide and continuous spectrum of proliferative β-cell changes. Moreover, we propose that uncooked cornstarch may offer an additional approach to alleviate the hypoglycemic episodes when surgery is impracticable/unaccepted.

Perspective on the Genetics and Diagnosis of Congenital Hyperinsulinism Disorders

CONTEXT

Congenital hyperinsulinism (HI) is the most common cause of hypoglycemia in children. The risk of permanent brain injury in infants with HI continues to be as high as 25-50% due to delays in diagnosis and inadequate treatment. Congenital HI has been described since the birth of the JCEM under various terms, including "idiopathic hypoglycemia of infancy," "leucine-sensitive hypoglycemia," or "nesidioblastosis."

EVIDENCE ACQUISITION

In the past 20 years, it has become apparent that HI is caused by genetic defects in the pathways that regulate pancreatic β-cell insulin secretion.

EVIDENCE SYNTHESIS

There are now 11 genes associated with monogenic forms of HI (ABCC8, KCNJ11, GLUD1, GCK, HADH1, UCP2, MCT1, HNF4A, HNF1A, HK1, PGM1), as well as several syndromic genetic forms of HI (eg, Beckwith-Wiedemann, Kabuki, and Turner syndromes). HI is also the cause of hypoglycemia in transitional neonatal hypoglycemia and in persistent hypoglycemia in various groups of high-risk neonates (such as birth asphyxia, small for gestational age birthweight, infant of diabetic mother). Management of HI is one of the most difficult problems faced by pediatric endocrinologists and frequently requires difficult choices, such as near-total pancreatectomy and/or highly intensive care with continuous tube feedings. For 50 years, diazoxide, a KATP channel agonist, has been the primary drug for infants with HI; however, it is ineffective in most cases with mutations of ABCC8 or KCNJ11, which constitute the majority of infants with monogenic HI.

CONCLUSIONS

Genetic mutation testing has become standard of care for infants with HI and has proven to be useful not only in projecting prognosis and family counseling, but also in diagnosing infants with surgically curable focal HI lesions. (18)F-fluoro-L-dihydroxyphenylalanine ((18)F-DOPA) PET scans have been found to be highly accurate for localizing such focal lesions preoperatively. New drugs under investigation provide hope for improving the outcomes of children with HI.

Lesson of the month 2: An unusual presentation of hyperinsulinaemic hypoglycaemia with possible underlying diagnosis of glucose-sensitive insulinoma or islet cell hyperplasia

Postprandial hypoglycaemia can occur in islet cell hyperplasia and in reactive hypoglycaemia. Less commonly, it can occur with insulinoma. A case is described where the differential diagnosis was glucose-sensitive insulinoma or islet cell hyperplasia. Typical provocation was prolonged exertion or fasting followed by ingestion of sugary snacks resulting in hypoglycaemic seizures and collapse. Biochemistry and computerised tomography imaging were consistent with an insulinoma in the pancreatic tail, but this was not confirmed on endoscopic ultrasound. Selective intra-arterial calcium stimulation with hepatic venous sampling results suggested a diagnosis of islet cell hyperplasia. Ten years later, repeat imaging was consistent with a neuroendocrine tumour. Surgical resection has resulted in remission of symptoms. The patient will be monitored long term to ensure no recurrence.

[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.

Treatment of hyperinsulinemic hypoglycemia because of diffuse nesidioblastosis with nifedipine after surgical therapies in a newborn

Recent studies have demonstrated a role for calcium channel blocking agents in the treatment of persistent hyperinsulinemic hypoglycemia of newborns. We report a newborn infant with persistent hyperinsulinemic hypoglycemia whom we successfully treated with oral nifedipine alone after surgical therapies. A 4-day-old male infant was referred with intractable hypoglycemia and seziures. Normoglycaemia could be maintained only by the intravenous infusion of glucose at a rate of 20 mg/kg per minute. Persistent hyperinsulinemic hypoglycemia of newborn was diagnosed from an inappropriately raised plasma insulin concentration (44 mU/L) at the time of hypoglycemia. Medical treatments led to only a mild reduction in the intravenous glucose requirement; an 85-90% pancreatectomy was performed and histological "diffuse nesidioblastosis" was confirmed. However, despite all the medical treatments after the first pancreatectomy, the hyperinsulinemic hypoglycemia persisted and a second 95% pancreatectomy was performed. After the second pancreatectomy, persistent hyperinsulinemic hypoglycemia was treated with somatostatin and diazoxide, but led to no reduction in the intravenous glucose requirement. We report the case of an infant who had persistent hypoglycemia after two subtotal pancreatic resections but subsequently became normoglycemic on treatment with nifedipine (2 mg/kg per day). The patient was discharged home on oral nifedipine. Calcium channel blocking agents cuold be used with efficacy and safety in recurrent persistent hyperinsulinemic hypoglycemia.

[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.

Current understanding of K ATP channels in neonatal diseases: focus on insulin secretion disorders

ATP-sensitive potassium (K(ATP)) channels are cell metabolic sensors that couple cell metabolic status to electric activity, thus regulating many cellular functions. In pancreatic beta cells, K(ATP) channels modulate insulin secretion in response to fluctuations in plasma glucose level, and play an important role in glucose homeostasis. Recent studies show that gain-of-function and loss-of-function mutations in K(ATP) channel subunits cause neonatal diabetes mellitus and congenital hyperinsulinism respectively. These findings lead to significant changes in the diagnosis and treatment for neonatal insulin secretion disorders. This review describes the physiological and pathophysiological functions of K(ATP) channels in glucose homeostasis, their specific roles in neonatal diabetes mellitus and congenital hyperinsulinism, as well as future perspectives of K(ATP) channels in neonatal diseases.

Clinical and molecular genetics of neonatal diabetes due to mutations in the insulin gene

Over the last decade our insight into the causes of neonatal diabetes has greatly expanded. Neonatal diabetes was once considered a variant of type 1 diabetes that presented early in life. Recent advances in our understanding of this disorder have established that neonatal diabetes is not an autoimmune disease, but rather is a monogenic form of diabetes resulting from mutations in a number of different genes encoding proteins that play a key role in the normal function of the pancreatic beta-cell. Moreover, a correct genetic diagnosis can affect treatment and clinical outcome. This is especially true for patients with mutations in the genes KCNJ11 or ABCC8 that encode the two protein subunits (Kir6.2 and SUR1, respectively) of the ATP-sensitive potassium channel. These patients can be treated with oral sulfonylurea drugs with better glycemic control and quality of life. Recently, mutations in the insulin gene (INS) itself have been identified as another cause of neonatal diabetes. In this article, we review the role of INS mutations in the pathophysiology of neonatal diabetes.

Mechanisms of Disease: advances in diagnosis and treatment of hyperinsulinism in neonates

Hyperinsulinism is the single most common mechanism of hypoglycemia in neonates. Dysregulated insulin secretion is responsible for the transient and prolonged forms of neonatal hypoglycemia, and congenital genetic disorders of insulin regulation represent the most common of the permanent disorders of hypoglycemia. Mutations in at least five genes have been associated with congenital hyperinsulinism: they encode glucokinase, glutamate dehydrogenase, the mitochondrial enzyme short-chain 3-hydroxyacyl-CoA dehydrogenase, and the two components (sulfonylurea receptor 1 and potassium inward rectifying channel, subfamily J, member 11) of the ATP-sensitive potassium channels (K(ATP) channels). K(ATP) hyperinsulinism is the most common and severe form of congenital hyperinsulinism. Infants suffering from K(ATP) hyperinsulinism present shortly after birth with severe and persistent hypoglycemia, and the majority are unresponsive to medical therapy, thus requiring pancreatectomy. In up to 40-60% of the children with K(ATP) hyperinsulinism, the defect is limited to a focal lesion in the pancreas. In these children, local resection results in cure with avoidance of the complications inherent to a near-total pancreatectomy. Hyperinsulinism can also be part of other disorders such as Beckwith-Wiedemann syndrome and congenital disorders of glycosylation. The diagnosis and management of children with congenital hyperinsulinism requires a multidisciplinary approach to achieve the goal of therapy: prevention of permanent brain damage due to recurrent hypoglycemia.

Insights in congenital hyperinsulinism

Congenital hyperinsulinism is characterized by the unregulated secretion of insulin from pancreatic Beta-cells. The inappropriate insulin secretion causes severe and persistent hypoglycaemia, which is a potent cause of brain damage if inappropriately managed. So far mutations in 5 different genes have been described which lead to inappropriate insulin secretion. The most common cause of congenital hyperinsulinism is autosomal recessive mutations in the genes ABCC8 and KCNJ11 encoding the 2 subunits (SUR 1 and Kir6.2, respectively) of the pancreatic Beta-cell ATP-sensitive potassium channel. Autosomal dominant mutations in the genes encoding glucokinase (GCK) and glutamate dehydrogenase (GLUD1) lead to inappropriate insulin secretion by increasing the ATP/ADP ratio in the Beta-cells. Autosomal recessive mutations in the HADHSC gene (encoding the enzyme short-chain L-3-hydroxyacyl-CoA dehydrogenase) have been linked to defects in fatty acid oxidation and hyperinsulinism. Finally some patients have been described with exerciseinduced hyperinsulinaemic hypoglycaemia but the genetic basis of this is unclear at present. Recent advances in 18fluoro-L-Dopa positron emission tomography scanning suggest that this is a highly sensitive method for differentiating diffuse from focal disease as well as accurately locating the focal lesion. Despite huge advances in the last 10 years the mechanisms leading to hyperinsulinaemic hypoglycaemia are still unknown in >50% of patients.

Multiple ectopic lesions of focal islet adenomatosis identified by positron emission tomography scan in an infant with congenital hyperinsulinism

Congenital hyperinsulinism (HI) exists in 2 histologic forms, focal and diffuse, and rarely has been attributed to lesions in ectopic pancreatic tissue. The ability to distinguish focal from diffuse HI and locate focal lesions has been difficult, thus limiting the optimal management of HI. We present a case of HI resulting from focal pancreatic and ectopic pancreatic lesions. After a near-total pancreatectomy failed to improve the patient's condition, a positron emission tomography (PET) scan performed with 18F-fluoro-L-dihydroxyphenylalanine demonstrated a focal lesion remaining in the head of the pancreas as well as 4 hot spots inferior to the remaining pancreas. Surgical exploration found pancreatic rests in the jejunum responsible for the hot spots seen on PET. Resection of the remainder of the pancreas as well as the small intestinal lesions resulted in correction of the patient's HI. Pathology confirmed the presence of focal HI lesions in the pancreatic head and small intestinal specimens. This case supports the ability of ectopic pancreatic tissue to contribute to the pathology of HI. It highlights the ability of PET to successfully identify focal lesions, including ectopic tissue, responsible for hyperinsulinemic hypoglycemia.

Persistent hyperinsulinemic hypoglycemia of infancy - nesidioblastosis

Persistent hyperinsulinemic hypoglycemia of infancy (PHHI) or nesidioblastosis is a rare condition presenting with severe hypoglycemia. Prompt diagnosis and early pancreatectomy can save many of them, in spite of the magnitude of surgery. We present two cases in which near total pancreatectomy was performed with favourable outcome. Both patients are normoglycemic, with one requiring pancreatic enzyme supplements.

Hyperinsulinemic hypoglycemia of infancy: the challenge continues

Hypoglycemia due to hyperinsulinemia is the most common cause of persistent hypoglycemia in infants and children. Recent discoveries in the molecular and biochemical regulation of insulin secretion have dramatically increased our understanding of the disorders responsible for syndromes of hyperinsulinemic hypoglycemia. Here, we briefly review the current knowledge of disorders of the K(ATP) channel, activating mutations of glucokinase and glutamate dehydrogenase (GDH) and other disorders that may be associated with specific phenotypes and permit appropriate targeted therapies. Despite these advances, much remains to be learned. We do not understand the mechanisms or defects in many instances, including defective carbohydrate glycosylation syndromes and perinatal hypoxia, both of which may be associated with hyperinsulinemia. Most importantly, preoperative distinction between diffuse and focal lesions cannot be always reliably made even after selective arterial infusion with calcium, glucose or a sulfonylurea with concurrent hepatic venous sampling for insulin. The ability to distinguish diffuse from localized lesions has profound implications for therapeutic approaches, prognosis and genetic counseling. To date, about 50% of individuals with hyperinsulinemic hypoglycemia of infancy can be correctly categorized. Thus, the challenge continues.