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Congenital secretory diarrhoea caused by activating germline mutations in GUCY2C.

ABSTRACT: OBJECTIVE:Congenital sodium diarrhoea (CSD) refers to a form of secretory diarrhoea with intrauterine onset and high faecal losses of sodium without congenital malformations. The molecular basis for CSD remains unknown. We clinically characterised a cohort of infants with CSD and set out to identify disease-causing mutations by genome-wide genetic testing. DESIGN:We performed whole-exome sequencing and chromosomal microarray analyses in 4 unrelated patients, followed by confirmatory Sanger sequencing of the likely disease-causing mutations in patients and in their family members, followed by functional studies. RESULTS:We identified novel de novo missense mutations in GUCY2C, the gene encoding receptor guanylate cyclase C (GC-C) in 4 patients with CSD. One patient developed severe, early-onset IBD and chronic arthritis at 4?years of age. GC-C is an intestinal brush border membrane-bound guanylate cyclase, which functions as receptor for guanylin, uroguanylin and Escherichia coli heat-stable enterotoxin. Mutations in GUCY2C were present in different intracellular domains of GC-C, and were activating mutations that enhanced intracellular cyclic guanosine monophosphate accumulation in a ligand-independent and ligand-stimulated manner, following heterologous expression in HEK293T cells. CONCLUSIONS:Dominant gain-of-function GUCY2C mutations lead to elevated intracellular cyclic guanosine monophosphate levels and could explain the chronic diarrhoea as a result of decreased intestinal sodium and water absorption and increased chloride secretion. Thus, mutations in GUCY2C indicate a role for this receptor in the pathogenesis of sporadic CSD.

SUBMITTER: Muller T

PROVIDER: S-EPMC4975829 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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Congenital secretory diarrhoea caused by activating germline mutations in GUCY2C.

Müller Thomas T Rasool Insha I Heinz-Erian Peter P Mildenberger Eva E Hülstrunk Christian C Müller Andreas A Michaud Laurent L Koot Bart G P BG Ballauff Antje A Vodopiutz Julia J Rosipal Stefan S Petersen Britt-Sabina BS Franke Andre A Fuchs Irene I Witt Heiko H Zoller Heinz H Janecke Andreas R AR Visweswariah Sandhya S SS

Gut 20150520 8

<h4>Objective</h4>Congenital sodium diarrhoea (CSD) refers to a form of secretory diarrhoea with intrauterine onset and high faecal losses of sodium without congenital malformations. The molecular basis for CSD remains unknown. We clinically characterised a cohort of infants with CSD and set out to identify disease-causing mutations by genome-wide genetic testing.<h4>Design</h4>We performed whole-exome sequencing and chromosomal microarray analyses in 4 unrelated patients, followed by confirmato ...[more]

PMID: 25994218

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Project description:BACKGROUND Familial diarrheas are mostly severe recessive diseases. Here we describe the clinical picture and dominant genetic cause of a novel disease in 32 members of a Norwegian family. The chronic diarrhea is of early onset, relatively mild, and is combined with increased susceptibility to intestinal inflammation, ileus and oesophagitis. METHODS Whole genome SNP-analysis was used to identify a single candidate locus for dominant diarrhea on chromosome 12, followed by sequencing of the GU2CY gene. This encodes guanylyl cyclase 2C, an intestinal receptor for bacterial heat-stable enterotoxins and the peptides uroguanylin and guanylin. Functional studies of a missense mutation were performed after heterologous expression of the mutant receptor in HEK293T cells. The therapeutic response to metformin, an inhibitor of the cystic fibrosis transmembrane regulator (CFTR), was investigated in 5 patients. RESULTS We identified heterozygosity for the first described pathogenic human mutation (c.2519G>T ) in the GUCY2C gene. The mutant receptor showed increased cGMP production in response to its ligands. This may cause hyperactivation of the CFTR and consequent increased chloride and water secretion from the enterocytes, resulting in chronic diarrhea. Treatment with the CFTR-inhibitor metformin significantly reduced the frequency of stools in affected individuals by 34-45%. CONCLUSIONS Increased GC-C signaling disturbs normal bowel function, as shown by the diverse symptoms in our patients, and seems to have a pro-inflammatory effect, either through increased Cl- secretion or additional effects of elevated cellular cGMP. The importance of genetic variants in the GC-C-CFTR-pathway for conditions like Crohn’s disease and IBS should be further explored. Linkage analysis was performed (Allegro v 2.0) using Affymetrix 250K SNP arrays according to the manufacturer's directions on DNA extracted from peripheral blood samples. This accession number contains the data for 25 individuals of family branch A in the article.

Dataset Information

Congenital secretory diarrhoea caused by activating germline mutations in GUCY2C.

Publications

Congenital secretory diarrhoea caused by activating germline mutations in GUCY2C.

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