Congenital hyperinsulinism in an infant with paternal uniparental disomy on chromosome 11p15: few clinical features suggestive of Beckwith-Wiedemann syndrome

Beckwith-Wiedemann Syndrome With Severe Relapsing Hypoglycemia After the Neonatal Period: A Case Report and a Literature Review

Beckwith-Wiedemann syndrome (BWS) is a rare genomic imprinting disorder that affects multiple systems. Major features can manifest as large birth weight, anterior abdominal wall defects, macroglossia, hyperinsulinism, organomegaly hemihypertrophy, and renal abnormalities. Characteristic facies manifested as midface hypoplasia, infraorbital creases, facial nevus simplex, and anterior linear ear lobe creases/posterior helical ear pits, with a predisposition to tumor development. This case report describes a Saudi infant born at 38+5 weeks gestation via elective cesarean section to a 33-year-old G3P2+0 mother, with a family history of type 1 diabetes and Down syndrome. Prenatal ultrasound revealed an anterior abdominal wall defect. Postnatally, the infant exhibited macrosomia, macroglossia, and omphalocele. Genetic testing confirmed paternal disomy of the imprinted region in 11p15.5. The infant underwent successful omphalocele repair but experienced respiratory distress, and seizures on the third day of life. Intubation, ventilation, and antiepileptic treatment were initiated. Subsequent investigations revealed right upper lobe collapse, neonatal seizures on electroencephalogram (EEG), and thin corpus callosum on magnetic resonance imaging (MRI). Feeding difficulties led to elective partial glossectomy at two months of age. During her hospital stay two days post surgery, the infant developed persistent hypoglycemia requiring high glucose infusion rates. Extensive endocrine evaluation revealed high insulin and cortisol levels. Subcutaneous octreotide was administered with minimal response. After 15 days of careful glucose tapering, the infant's blood glucose stabilized, reaching feeding targets. The patient was discharged with follow-up appointments. This comprehensive case highlights the complexity of managing severe relapsing hypoglycemia in an infant with BWS.

Syndromic forms of congenital hyperinsulinism

Congenital hyperinsulinism (CHI), also called hyperinsulinemic hypoglycemia (HH), is a very heterogeneous condition and represents the most common cause of severe and persistent hypoglycemia in infancy and childhood. The majority of cases in which a genetic cause can be identified have monogenic defects affecting pancreatic β-cells and their glucose-sensing system that regulates insulin secretion. However, CHI/HH has also been observed in a variety of syndromic disorders. The major categories of syndromes that have been found to be associated with CHI include overgrowth syndromes (e.g. Beckwith-Wiedemann and Sotos syndromes), chromosomal and monogenic developmental syndromes with postnatal growth failure (e.g. Turner, Kabuki, and Costello syndromes), congenital disorders of glycosylation, and syndromic channelopathies (e.g. Timothy syndrome). This article reviews syndromic conditions that have been asserted by the literature to be associated with CHI. We assess the evidence of the association, as well as the prevalence of CHI, its possible pathophysiology and its natural course in the respective conditions. In many of the CHI-associated syndromic conditions, the mechanism of dysregulation of glucose-sensing and insulin secretion is not completely understood and not directly related to known CHI genes. Moreover, in most of those syndromes the association seems to be inconsistent and the metabolic disturbance is transient. However, since neonatal hypoglycemia is an early sign of possible compromise in the newborn, which requires immediate diagnostic efforts and intervention, this symptom may be the first to bring a patient to medical attention. As a consequence, HH in a newborn or infant with associated congenital anomalies or additional medical issues remains a differential diagnostic challenge and may require a broad genetic workup.

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.

Investigation of (epi)genotype causes and follow-up manifestations in the patients with classical and atypical phenotype of Beckwith-Wiedemann spectrum

Beckwith-Wiedemann syndrome (BWS) is a genomic imprinting disorder, characterized by macroglossia, abdominal wall defects, lateralized overgrowth, and predisposition to embryonal tumors. It is caused by the defect of imprinted genes on chromosome 11p15.5, regulated by imprinting control (IC) domains, IC1, and IC2. Rarely, CDKN1C and chromosomal changes can be detected. The aim of this study is to retrospectively evaluate 55 patients with BWS using the new diagnostic criteria developed by the BWS consensus, and to investigate (epi)genetic changes and follow-up findings in classic and atypical phenotypes. Loss of methylation in IC2 region (IC2-LoM), 11p15.5 paternal uniparental disomy (pUPD11), and methylation gain in IC1 region (IC1-GoM) are detected in 31, eight, and five patients, respectively. Eleven patients have had no molecular defects. Thirty-five patients are classified as classical and 20 as atypical phenotype. Patients with classical phenotype are more frequent in the IC2-LoM (25/31), while patients with atypical phenotype are common in the pUPD11 group (5/8). Malignant tumors have developed in six patients (10.9%); three of these patients have IC1-GoM, two pUPD11, one IC2-LoM genotype, and four an atypical phenotype. We observed that the face was round in the infantile period and elongated as the child grew-up, developing prognathism and becoming asymmetrical if hemi-macroglossia was present in the classical phenotype. These findings were mild in the atypical phenotype. These results support the importance of using the new diagnostic criteria to facilitate the diagnosis of patients with atypical phenotype who have higher tumors risk. This study also provides important information about facial gestalt.

The Genetic and Molecular Mechanisms of Congenital Hyperinsulinism

Congenital hyperinsulinism (CHI) is a heterogenous and complex disorder in which the unregulated insulin secretion from pancreatic beta-cells leads to hyperinsulinaemic hypoglycaemia. The severity of hypoglycaemia varies depending on the underlying molecular mechanism and genetic defects. The genetic and molecular causes of CHI include defects in pivotal pathways regulating the secretion of insulin from the beta-cell. Broadly these genetic defects leading to unregulated insulin secretion can be grouped into four main categories. The first group consists of defects in the pancreatic KATP channel genes (ABCC8 and KCNJ11). The second and third categories of conditions are enzymatic defects (such as GDH, GCK, HADH) and defects in transcription factors (for example HNF1α, HNF4α) leading to changes in nutrient flux into metabolic pathways which converge on insulin secretion. Lastly, a large number of genetic syndromes are now linked to hyperinsulinaemic hypoglycaemia. As the molecular and genetic basis of CHI has expanded over the last few years, this review aims to provide an up-to-date knowledge on the genetic causes of CHI.

Epigenetics and Metabolism in Health and Disease

In the next 10 years, one billion people are estimated to suffer from disabling consequences of metabolic disorders, making them the number one noncommunicable disease on a global scale by 2030. Lots of risk factors such as dietary intake, lack of exercise and other life style behaviors are considered to play a role in the development of metabolic disorders. Despite the efforts that have been undertaken to unravel their potential causes, the underlying molecular mechanisms remain elusive. Evidence suggests that the pathogenesis involves changes on chromatin and chromatin-modifying enzymes, which can contribute to a persistent dysregulated metabolic phenotype. Indeed, a rising number of studies links epigenetic alterations with the diagnosis and prognosis of metabolic disorders. A prerequisite for exploiting these findings for pharmacological intervention is a detailed understanding of how differential epigenetic modifications control cell metabolism. In this mini review, we summarize the recent advances in uncovering the interplay between epigenetics and metabolic pathways on a cellular level and highlight potential new avenues for alternative treatment strategies.

Severe Hyperinsulinaemic Hypoglycaemia in Beckwith-Wiedemann Syndrome due to Paternal Uniparental Disomy of 11p15.5 Managed with Sirolimus Therapy

BACKGROUND

Almost half of the children with Beckwith-Wiedemann syndrome (BWS) will develop hyperinsulinaemic hypoglycaemia (HH). In the majority of BWS cases, HH will be transient; however, approximately in 5% of them, HH will be severe and often medically-unresponsive. Children with BWS due to paternal uniparental disomy (UPD) of chromosome 11p15 belong to this severe category and have traditionally required near-total pancreatectomy. The use of mTOR inhibitors had not been reported yet in this type of patients.

CASE

A 1-month-old female with genetically confirmed BWS due to UPD of chromosome 11p15 was admitted for management of severe HH. Blood glucose concentrations were stabilised with high intravenous dextrose concentration, glucagon and octreotide infusions as she was proven to be diazoxide unresponsive. To avoid a subtotal pancreatectomy, an mTOR inhibitor - sirolimus - was introduced. The dose of sirolimus was optimised progressively and she was able to come off intravenous fluids and glucagon therapy. She has not presented any side effects and her growth is normal after 19 months of therapy.

CONCLUSION

This is the first case reported of BWS due to UPD of chromosome 11p15 where sirolimus treatment has been effective in stabilising the blood glucose concentrations and avoiding a near-total pancreatectomy without major side effects detected.

Another Preemie with Hypoglycemia? Beckwith-Wiedemann Syndrome--A Case Study

Beckwith-Wiedemann syndrome (BWS) is the most common overgrowth disorder in infants. This article reviews a case of a premature infant with an atypical presentation of Beckwith-Wiedemann that was diagnosed at one month of age. It also addresses notable aspects of the etiology, diagnosis, and management of infants with BWS.

Congenital hyperinsulinism in children with paternal 11p uniparental isodisomy and Beckwith-Wiedemann syndrome

BACKGROUND

Congenital hyperinsulinism (HI) can have monogenic or syndromic causes. Although HI has long been recognised to be common in children with Beckwith-Wiedemann syndrome (BWS), the underlying mechanism is not known.

METHODS

We characterised the clinical features of children with both HI and BWS/11p overgrowth spectrum, evaluated the contribution of KATP channel mutations to the molecular pathogenesis of their HI and assessed molecular pathogenesis associated with features of BWS.

RESULTS

We identified 28 children with HI and BWS/11p overgrowth from 1997 to 2014. Mosaic paternal uniparental isodisomy for chromosome 11p (pUPD11p) was noted in 26/28 cases. Most were refractory to diazoxide treatment and half required subtotal pancreatectomies. Patients displayed a wide range of clinical features from classical BWS to only mild hemihypertrophy (11p overgrowth spectrum). Four of the cases had a paternally transmitted KATP mutation and had a much more severe HI course than patients with pUPD11p alone.

CONCLUSIONS

We found that patients with pUPD11p-associated HI have a persistent and severe HI phenotype compared with transient hypoglycaemia of BWS/11p overgrowth patients caused by other aetiologies. Testing for pUPD11p should be considered in all patients with persistent congenital HI, especially for those without an identified HI gene mutation.

Mosaic paternal genome-wide uniparental isodisomy with down syndrome

We report on a 6-month-old girl with two apparent cell lines; one with trisomy 21, and the other with paternal genome-wide uniparental isodisomy (GWUPiD), identified using single nucleotide polymorphism (SNP) based microarray and microsatellite analysis of polymorphic loci. The patient has Beckwith-Wiedemann syndrome (BWS) due to paternal uniparental disomy (UPD) at chromosome location 11p15 (UPD 11p15), which was confirmed through methylation analysis. Hyperinsulinemic hypoglycemia is present, which is associated with paternal UPD 11p15.5; and she likely has medullary nephrocalcinosis, which is associated with paternal UPD 20, although this was not biochemically confirmed. Angelman syndrome (AS) analysis was negative but this testing is not completely informative; she has no specific features of AS. Clinical features of this patient include: dysmorphic features consistent with trisomy 21, tetralogy of Fallot, hemihypertrophy, swirled skin hyperpigmentation, hepatoblastoma, and Wilms tumor. Her karyotype is 47,XX,+21[19]/46,XX[4], and microarray results suggest that the cell line with trisomy 21 is biparentally inherited and represents 40-50% of the genomic material in the tested specimen. The difference in the level of cytogenetically detected mosaicism versus the level of mosaicism observed via microarray analysis is likely caused by differences in the test methodologies. While a handful of cases of mosaic paternal GWUPiD have been reported, this patient is the only reported case that also involves trisomy 21. Other GWUPiD patients have presented with features associated with multiple imprinted regions, as does our patient.

Insulin-like growth factor-II: its role in metabolic and endocrine disease

Insulin-like growth factor-II (IGF-II) is a widely expressed 7·5 kDa mitogenic peptide hormone. Although it is abundant in serum, understanding of its physiological role is limited compared with that of IGF-I. IGF-II regulates foetal development and differentiation, but its role in adults is less well understood. Evidence suggests roles in a number of tissues including skeletal muscle, adipose tissue, bone and ovary. Altered IGF-II expression has been observed in metabolic conditions, notably obesity, diabetes and the polycystic ovary syndrome. This article summarizes what is known about the actions of IGF-II and its dysregulation in metabolic and endocrine diseases. The possible causes and consequences of dysregulation are discussed along with the implications for diagnostic tests and future research.