Persistent congenital hyperinsulinism in two patients with Beckwith-Wiedemann syndrome due to mosaic uniparental disomy 11p

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.

Somatostatin analogues for the treatment of hyperinsulinaemic hypoglycaemia

Hyperinsulinaemic hypoglycaemia (HH) is a biochemical finding of low blood glucose levels due to the dysregulation of insulin secretion from pancreatic β-cells. Under normal physiological conditions, glucose metabolism is coupled to β-cell insulin secretion so that blood glucose levels are maintained within the physiological range of 3.5-5.5 mmol/L. However, in HH this coupling of glucose metabolism to insulin secretion is perturbed so that insulin secretion becomes unregulated. HH typically occurs in the neonatal, infancy and childhood periods and can be due to many different causes. Adults can also present with HH but the causes in adults tend to be different. Somatostatin (SST) is a peptide hormone that is released by the delta cells (δ-cells) in the pancreas. It binds to G protein-coupled SST receptors to regulate a variety of location-specific and selective functions such as hormone inhibition, neurotransmission and cell proliferation. SST plays a potent role in the regulation of both insulin and glucagon secretion in response to changes in glucose levels by negative feedback mechanism. The half-life of SST is only 1-3 min due to quick degradation by peptidases in plasma and tissues. Thus, a direct continuous intravenous or subcutaneous infusion is required to achieve the therapeutic effect. These limitations prompted the discovery of SST analogues such as octreotide and lanreotide, which have longer half-lives and therefore can be administered as injections. SST analogues are used to treat different forms of HH in children and adults and therapeutic effect is achieved by suppressing insulin secretion from pancreatic β-cells by complex mechanisms. These treatments are associated with several side effects, especially in the newborn period, with necrotizing enterocolitis being the most serious side effect and hence SS analogues should be used with extreme caution in this age group.

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.

Successful use of long acting octreotide in two cases with Beckwith-Wiedemann syndrome and severe hypoglycemia

INTRODUCTION

Hyperinsulinism associated with Beckwith-Wiedemann syndrome (BWS) can occur in about 50% of cases, causing hypoglycemia of variable severity. Parenteral use of octreotide may be indicated if unresponsive to diazoxide. There is limited data on use of octreotide in BWS.

OBJECTIVE

Chart review describing 2 cases with BWS and hypoglycemia treated with long acting Octreotide as a monthly injection.

CASES

We describe two unrelated females born large for gestational age found to have clinical features consistent with BWS, who developed severe hypoglycemia. Genetic diagnosis of BWS was confirmed. The first patient was born at 37 weeks and developed hypoglycemia shortly after birth. She was initially started on diazoxide but developed pulmonary congestion and was therefore switched to depot octreotide (LAR). She maintained euglycemia with LAR. In the second patient (born at 26-4/7 weeks), onset of hypoglycemia was delayed till 11 weeks of age due to hydrocortisone (indicated hemodynamically) and continuous feeding, and was partially responsive to diazoxide. She was switched to octreotide 4 times daily, treated till at age 18 months. Despite frequent feeds, she required treatment again between ages 4-6.5 years, initially with diazoxide but due to severe hypertrichosis she was switched to LAR with an excellent response. Both patients treated with LAR for over two years achieved euglycemia above 70 mg/dl and had normal height gain, without side effects.

CONCLUSION

Successful treatment of hypoglycemia can be achieved and maintained with LAR in infants and children with BWS who are either resistant or cannot tolerate diazoxide.