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Congenital Sodium Diarrhea: A Form of Intractable Diarrhea, With a Link to Inflammatory Bowel Disease
Andreas R Janecke1, Peter Heinz-Erian, Thomas Müller
1*Department of Pediatrics I, Medical University of Innsbruck †Division of Human Genetics, Medical University of Innsbruck, Innsbruck, Austria.
Insights
Congenital diarrheal disorders (CDDs) are severe conditions caused by intestinal transport defects. Recent advances identify genetic causes like SPINT2, GUCY2C, and SLC9A3 mutations, enabling earlier diagnosis and understanding of inflammatory bowel disease links.
Area of Science:
- Pediatric gastroenterology
- Human genetics
- Molecular biology
Background:
- Congenital diarrheal disorders (CDDs) present significant diagnostic challenges in pediatrics due to severe symptoms and diverse causes.
- CDDs stem from defects in intestinal nutrient/electrolyte transport, enterocyte differentiation, or immune response modulation.
- Recent progress has elucidated the genetic basis of congenital sodium diarrhea (CSD), a severe intrauterine-onset diarrhea with high fecal sodium loss.
Purpose of the Study:
- To review recent advances in understanding the etiology and pathophysiology of congenital diarrheal disorders, focusing on congenital sodium diarrhea.
- To highlight the genetic heterogeneity of CSD, including syndromic and nonsyndromic forms.
- To discuss the implications of identified CDD genes for diagnosis and potential links to inflammatory bowel disease.
Main Methods:
- Literature review of recent studies on CDDs and CSD.
- Analysis of genetic mutations associated with CSD, including SPINT2, GUCY2C, and SLC9A3.
- Review of clinical presentations, histological findings, and inheritance patterns.
Main Results:
- CSD is genetically heterogeneous, caused by SPINT2 mutations (syndromic form with atresias and corneal erosions) or GUCY2C/SLC9A3 mutations (nonsyndromic form).
- SPINT2 mutations lead to syndromic CSD with epithelial "tufting" dysplasia.
- GUCY2C (guanylate cyclase C) and SLC9A3 (Na/H antiporter 3) mutations are implicated in nonsyndromic CSD, with some patients developing inflammatory bowel disease.
- The number of identified CDD genes and forms is increasing.
Conclusions:
- Advances in genetic discovery facilitate early diagnosis of CDDs through next-generation gene panel testing.
- SPINT2, GUCY2C, and SLC9A3 mutations are key genetic causes of CSD.
- Malfunction of Na/H antiporter 3 and GC-C may predispose a subset of patients to inflammatory bowel disease.
Abstract:
Congenital diarrheal disorders (CDDs) represent a group of challenging clinical conditions for pediatricians because of the severity of the presentation and the broad range of possible differential diagnoses. CDDs arise from alterations in the transport of nutrients and electrolytes across the intestinal mucosa, from enterocyte and enteroendocrine cell differentiation and/or polarization defects, and from the modulation of the intestinal immune response. Advances were made recently in deciphering the etiology and pathophysiology of one of these disorders, congenital sodium diarrhea (CSD). CSD refers to an intractable diarrhea of intrauterine onset with high fecal sodium loss. CSD is clinically and genetically heterogeneous. A syndromic form of CSD features choanal and intestinal atresias as well as recurrent corneal erosions. Small bowel histology frequently detects an epithelial "tufting" dysplasia. It is autosomal recessively inherited, and caused by SPINT2 mutations. The nonsyndromic form of CSD can be caused by dominant activating mutations in GUCY2C, encoding intestinal receptor guanylate cyclase C (GC-C), and by autosomal recessive SLC9A3 loss-of-function mutations. SLC9A3 encodes Na/H antiporter 3, the major intestinal brush border Na/H exchanger, and a downstream target of GC-C. A number of patients with GUCY2C and SLC9A3 mutations developed inflammatory bowel disease. Both the number of recognized CDD forms as well as the number of underlying disease genes are gradually increasing. Knowledge of these CDD genes enables noninvasive, next-generation gene panel-based testing to facilitate an early diagnosis in CDD. Primary Na/H antiporter 3 and GC-C malfunction is implicated as a predisposition for inflammatory bowel disease in subset of patients.
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