Atypical Forms of Congenital Hyperinsulinism in Infancy Are Associated With Mosaic Patterns of Immature Islet Cells

J Clin Endocrinol Metab. 2017 Sep 1;102(9):3261-3267. doi: 10.1210/jc.2017-00158.


Objectives: We aimed to characterize mosaic populations of pancreatic islet cells from patients with atypical congenital hyperinsulinism in infancy (CHI-A) and the expression profile of NKX2.2, a key transcription factor expressed in β-cells but suppressed in δ-cells in the mature pancreas.

Patients/methods: Tissue was isolated from three patients with CHI-A following subtotal pancreatectomy. CHI-A was diagnosed on the basis of islet mosaicism and the absence of histopathological hallmarks of focal and diffuse CHI (CHI-D). Immunohistochemistry was used to identify and quantify the proportions of insulin-secreting β-cells and somatostatin-secreting δ-cells in atypical islets, and results were compared with CHI-D (n = 3) and age-matched control tissues (n = 3).

Results: In CHI-A tissue, islets had a heterogeneous profile. In resting/quiescent islets, identified by a condensed cytoplasm and nuclear crowding, β-cells were reduced to <50% of the total cell numbers in n = 65/70 islets, whereas δ-cell numbers were increased with 85% of islets (n = 49/57) containing >20% δ-cells. In comparison, all islets in control tissue (n = 72) and 99% of CHI-D islets (n = 72) were composed of >50% β-cells, and >20% δ-cells were found only in 12% of CHI-D (n = 8/66) and 5% of control islets (n = 3/60). Active islets in CHI-A tissue contained proportions of β-cells and δ-cells similar to those of control and CHI-D islets. Finally, when compared with active islets, quiescent islets had a twofold higher prevalence of somatostatin/NKX2.2+ coexpressed cells.

Conclusions: Marked increases in NKX2.2 expression combined with increased numbers of δ-cells strongly imply that an immature δ-cell profile contributed to the pathobiology of CHI-A.

MeSH terms

  • Biopsy, Needle
  • Child, Preschool
  • Cohort Studies
  • Congenital Hyperinsulinism / genetics*
  • Congenital Hyperinsulinism / pathology*
  • Congenital Hyperinsulinism / surgery
  • Female
  • Genetic Predisposition to Disease*
  • Humans
  • Immunohistochemistry
  • Infant
  • Islets of Langerhans / metabolism
  • Islets of Langerhans / pathology*
  • Male
  • Mosaicism
  • Nuclear Proteins / genetics*
  • Pancreatectomy / methods
  • Prognosis
  • Reference Values
  • Severity of Illness Index
  • Thyroid Nuclear Factor 1
  • Transcription Factors / genetics*


  • Nuclear Proteins
  • Thyroid Nuclear Factor 1
  • Transcription Factors