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.
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.
Project description:A novel mouse harbouring a mutation in receptor guanylyl cyclase C (Gucy2c) that is equivalent to that seen in patients with Familial GUCY2C syndrome was established. Since patients are susceptible to colitis-like disease and IBD, RNAseq was performed on the distal colon in these mice to identify global transcriptome changes that arise as a consequence of this mutation Gucy2c.
Project description:The experiment was designed to detemine changes in gene expression between wild type mice and mice with a mutation in receptor guanylyl cyclase C at the Serine 839 position converted to an Isoleucine. This mutation mimics the mutation seen in human patients with familial GUCY2C diarrhoea syndrome.
Project description:Organoids were prepared from the small intestine of wild type C57BL6N mice and mice harbouring an activating mutation in Gucy2c that converts a serine at position 839 to an isoleucine. Organoids were treated with 1 micromolar uroguanylin for 18h. RNA was prepared and subjected to RNAseq analysis.
Project description:Patients with chronic illnesses such as Irritable Bowel Syndrome (IBS) or Inflammatory Bowel Disease (IBD) often have reduced quality of life. IBS is characterized by abdominal pain/discomfort associated with altered bowel function, such as diarrhea or constipation, without gross structural changes or inflammation [1]; IBD is characterized by gross inflammation in the gastrointestinal (GI) tract which can result in symptoms such as abdominal pain, cramping, diarrhea and bloody stools. IBS and IBD can profoundly affect quality of life and are influenced by stress and resiliency.The impact of mind-body interventions (MBIs) on IBS and IBD patients has not previously been examined. In this study IBS and IBD patients were enrolled in a 9-week relaxation response based mind-body group intervention (RR-MBI), focusing on elicitation of the RR and cognitive skill building. We performed Peripheral blood transcriptome analysis to identify genomic correlates of the RR-MBI.
