Diffuse congenital hyperinsulinism in infancy (CHI-D) arises from mutations inactivating the KATP channel; however, the phenotype is difficult to explain from electrophysiology alone. Here we studied wider abnormalities in the b-cell and other pancreatic lineages. Islets were disorganized in CHI-D compared with controls. PAX4 and ARX expression was decreased. A tendency toward increased NKX2.2 expression was consistent with its detection in two-thirds of CHI-D δ-cell nuclei, similar to the fetal pancreas, and implied immature d-cell function. CHI-D δ-cells also comprised 10% of cells displaying nucleomegaly. In CHI-D, increased proliferation was most elevated in duct (5-to 11-fold) and acinar (7-to 47-fold) lineages. Increased β-cell proliferation observed in some cases was offset by an increase in apoptosis; this is in keeping with no difference in INSULIN expression or surface area stained for insulin between CHI-D and control pancreas. However, nuclear localization of CDK6 and P27 was markedly enhanced in CHI-D β-cells compared with cytoplasmic localization in control cells. These combined data support normal β-cell mass in CHI-D, but with G1/S molecules positioned in favor of cell cycle progression. New molecular abnormalities in δ-cells and marked proliferative increases in other pancreatic lineages indicate CHI-D is not solely a β-cell disorder.

doi.org/10.2337/db14-1202, hdl.handle.net/1765/88146
Erasmus MC: University Medical Center Rotterdam

Salisbury, R. J., Han, B., Jennings, R. E., Berry, A. A., Stevens, A., Mohamed, Z., … Hanley, N. A. (2015). Altered phenotype of β-cells and other pancreatic cell lineages in patients with diffuse congenital hyperinsulinism in infancy caused by mutations in the ATP-sensitive K-channel. Diabetes, 64(9), 3182–3188. doi:10.2337/db14-1202