Case Report: Two Distinct Focal Congenital Hyperinsulinism Lesions Resulting From Separate Genetic Events

Congenital Hyperinsulinism Caused by Mutations in ABCC8 Gene Associated with Early-Onset Neonatal Hypoglycemia: Genetic Heterogeneity Correlated with Phenotypic Variability

Congenital hyperinsulinism (CHI) is a rare disorder of glucose metabolism and is the most common cause of severe and persistent hypoglycemia (hyperinsulinemic hypoglycemia, HH) in the neonatal period and childhood. Most cases are caused by mutations in the ABCC8 and KCNJ11 genes that encode the ATP-sensitive potassium channel (KATP). We present the correlation between genetic heterogeneity and the variable phenotype in patients with early-onset HH caused by ABCC8 gene mutations. In the first patient, who presented persistent severe hypoglycemia since the first day of life, molecular genetic testing revealed the presence of a homozygous mutation in the ABCC8 gene [deletion in the ABCC8 gene c.(2390+1_2391-1)_(3329+1_3330-1)del] that correlated with a diffuse form of hyperinsulinism (the parents being healthy heterozygous carriers). In the second patient, the onset was on the third day of life with severe hypoglycemia, and genetic testing identified a heterozygous mutation in the ABCC8 gene c.1792C>T (p.Arg598*) inherited on the paternal line, which led to the diagnosis of the focal form of hyperinsulinism. To locate the focal lesions, (18)F-DOPA (3,4-dihydroxy-6-[18F]fluoro-L-phenylalanine) positron emission tomography/computed tomography (PET/CT) was recommended (an investigation that cannot be carried out in the country), but the parents refused to carry out the investigation abroad. In this case, early surgical treatment could have been curative. In addition, the second child also presented secondary adrenal insufficiency requiring replacement therapy. At the same time, she developed early recurrent seizures that required antiepileptic treatment. We emphasize the importance of molecular genetic testing for diagnosis, management and genetic counseling in patients with HH.

Functional Regulation of KATP Channels and Mutant Insight Into Clinical Therapeutic Strategies in Cardiovascular Diseases

ATP-sensitive potassium channels (K_ATP channels) play pivotal roles in excitable cells and link cellular metabolism with membrane excitability. The action potential converts electricity into dynamics by ion channel-mediated ion exchange to generate systole, involved in every heartbeat. Activation of the K_ATP channel repolarizes the membrane potential and decreases early afterdepolarization (EAD)-mediated arrhythmias. K_ATP channels in cardiomyocytes have less function under physiological conditions but they open during severe and prolonged anoxia due to a reduced ATP/ADP ratio, lessening cellular excitability and thus preventing action potential generation and cell contraction. Small active molecules activate and enhance the opening of the K_ATP channel, which induces the repolarization of the membrane and decreases the occurrence of malignant arrhythmia. Accumulated evidence indicates that mutation of K_ATP channels deteriorates the regulatory roles in mutation-related diseases. However, patients with mutations in K_ATP channels still have no efficient treatment. Hence, in this study, we describe the role of K_ATP channels and subunits in angiocardiopathy, summarize the mutations of the K_ATP channels and the functional regulation of small active molecules in K_ATP channels, elucidate the potential mechanisms of mutant K_ATP channels and provide insight into clinical therapeutic strategies.

Correlation of PET-MRI, pathology, LOH and surgical success in a case of CHI with atypical large pancreatic focus

Congenital hyperinsulinism (CHI) is a rare cause of severe hypoglycemia in newborns. In focal CHI, usually one activity peak in fluorine-18-L-dihydroxyphenylalanine (¹⁸F-DOPA) positron emission tomography–magnetic resonance imaging (PET-MRI) indicates one focal lesion and its resection results in cure of the child. We present the case of a 5-month-old girl with CHI. Mutational screening of genes involved in CHI revealed a heterozygous pathogenic variant in the ABCC8 gene, which was not detectable in the parents. ¹⁸F-DOPA PET-MRI revealed 2 distinct activity peaks nearby in the pancreatic body and neck. Surgical resection of the tissue areas representing both activity peaks resulted in long-lasting normoglycemia that was proven by a fasting test. Molecular analysis of tissue samples from various sites provided evidence that a single second genetic hit in a pancreatic precursor cell was responsible for the atypical extended pancreatic lesion. There was a close correlation in the resected areas of PET-MRI activity with focal histopathology and frequency of the mutant allele (loss of heterozygosity) in the tissue. Focal lesions can be very heterogenous. The resection of the most affected areas as indicated by imaging, histopathology, and genetics could result in complete cure.

Congenital hyperinsulinism in clinical practice: From biochemical pathophysiology to new monitoring techniques

Congenital hyperinsulinism comprises a group of diseases characterized by a persistent hyperinsulinemic hypoglycemia, due to mutation in the genes involved in the regulation of insulin secretion. The severity and the duration of hypoglycemic episodes, primarily in the neonatal period, can lead to neurological impairment. Detecting blood sugar is relatively simple but, unfortunately, symptoms associated with hypoglycemia may be non-specific. Research in this field has led to novel insight in diagnosis, monitoring and treatment, leading to a better neurological outcome. Given the increased availability of continuous glucose monitoring systems that allow glucose level recognition in a minimally invasive way, monitoring the glycemic trend becomes easier and there are more possibilities of a better follow-up of patients. We aim to provide an overview of new available technologies and new discoveries and their potential impact on clinical practice, convinced that only with a better awareness of the disease and available tools we can have a better impact on CHI diagnosis, prevention and clinical sequelae.