Hyperinsulinemic Hypoglycemia and Growth Hormone Deficiency Secondary to 20p11 Deletion

Chromosome 20p11.2 deletions cause congenital hyperinsulinism via the loss of FOXA2 or its regulatory elements

Persistent congenital hyperinsulinism (HI) is a rare genetically heterogeneous condition characterised by dysregulated insulin secretion leading to life-threatening hypoglycaemia. For up to 50% of affected individuals screening of the known HI genes does not identify a disease-causing variant. Large deletions have previously been used to identify novel regulatory regions causing HI. Here, we used genome sequencing to search for novel large (>1 Mb) deletions in 180 probands with HI of unknown cause and replicated our findings in a large cohort of 883 genetically unsolved individuals with HI using off-target copy number variant calling from targeted gene panels. We identified overlapping heterozygous deletions in five individuals (range 3-8 Mb) spanning chromosome 20p11.2. The pancreatic beta-cell transcription factor gene, FOXA2, a known cause of HI was deleted in two of the five individuals. In the remaining three, we found a minimal deleted region of 2.4 Mb adjacent to FOXA2 that encompasses multiple non-coding regulatory elements that are in conformational contact with FOXA2. Our data suggests that the deletions in these three children may cause disease through the dysregulation of FOXA2 expression. These findings provide new insights into the regulation of FOXA2 in the beta-cell and confirm an aetiological role for chromosome 20p11.2 deletions in syndromic HI.

Factors associated with neonatal hyperinsulinemic hypoglycemia, a case-control study

OBJECTIVES

We aimed to identify perinatal risk factors associated with hyperinsulinemic hypoglycemia in neonates. Secondary objectives included an examination of clinical and biochemical characteristics at the time of diagnosis and an exploration of the duration of diazoxide therapy.

METHODS

A case-control study was conducted, involving individual chart reviews of inborn infants diagnosed with hyperinsulinemic hypoglycemia (the HH group) between 2014 and 2021. These cases were paired with controls (the non-HH group) belonging to the same gestational age (GA) strata who did not exhibit HH or only had transient postnatal hypoglycemia.

RESULTS

A total of 52 infants with HH were matched with corresponding controls. The mean GA in the HH group was 34.4 ± 3.1 weeks. Notably, the HH group exhibited lower mean minimum plasma glucose (PG) levels and required higher glucose infusion rates in comparison to the non-HH group (26.5 ± 15.6 vs. 49.1 ± 37.7 mg/dL and 12.9 ± 3.8 vs. 5.7 ± 2.1 mg/kg/min, respectively; p<0.001 for both). After adjusting for potential confounding factors, only two variables, fetal growth restriction (FGR) and neonatal sepsis, demonstrated significant associations with HH (adjusted odds ratio [95 % confidence interval]: 8.1 [2.1-31.0], p=0.002 and 6.3 [1.9-21.4], p=0.003, respectively). The median duration of diazoxide therapy for the HH group was 4 months.

CONCLUSIONS

FGR and neonatal sepsis emerged as notable risk factors for HH. These infants exhibited lower PG levels and necessitated higher glucose infusion rates compared to their non-HH counterparts. Importantly, a substantial proportion of the HH group received diazoxide therapy, with a median treatment duration of 4 months.