Chromogranin-A staining reveals enteric anendocrinosis in unexplained congenital diarrhea

A Comprehensive Structure-Function Study of Neurogenin3 Disease-Causing Alleles during Human Pancreas and Intestinal Organoid Development

Neurogenin3 (NEUROG3) is required for endocrine lineage formation of the pancreas and intestine. Patients with NEUROG3 mutations are born with congenital malabsorptive diarrhea due to complete loss of enteroendocrine cells, whereas endocrine pancreas development varies in an allele-specific manner. These findings suggest a context-dependent requirement for NEUROG3 in pancreas versus intestine. We utilized human tissue differentiated from NEUROG3^-/- pluripotent stem cells for functional analyses. Most disease-associated alleles had hypomorphic or null phenotype in both tissues, whereas the S171fsX68 mutation had reduced activity in the pancreas but largely null in the intestine. Biochemical studies revealed NEUROG3 variants have distinct molecular defects with altered protein stability, DNA binding, and gene transcription. Moreover, NEUROG3 was highly unstable in the intestinal epithelium, explaining the enhanced sensitivity of intestinal defects relative to the pancreas. These studies emphasize that studies of human mutations in the endogenous tissue context may be required to assess structure-function relationships.

Extremely rare cause of congenital diarrhea: enteric anendocrinosis

Congenital diarrheal disorders consist of a variety of chronic enteropathies. There are approximately 30 different diseases that can be classified into four groups according to the mechanisms involved in pathogenesis: (i) absorption and transport of nutrients and electrolytes; (ii) enterocyte differentiation and polarization; (iii) enteroendocrine cell differentiation; and (iv) modulation of the intestinal immune response. Affected patients often present with life-threatening diarrhea, in the first few weeks of life. A new disorder, enteric anendocrinosis, which is characterized by severe malabsorptive diarrhea and a lack of intestinal enteroendocrine cells has recently been described in six patients with recessively inherited mutations in the Neurogenin-3 gene. In this report we describe a seventh case with a review of the literature.