guanosine-monophosphate and Abnormalities--Multiple

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.. 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.. 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.. 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.

Topics: Abnormalities, Multiple; Diarrhea; Female; Genetic Predisposition to Disease; Guanosine Monophosphate; Humans; Infant; Intestinal Absorption; Intestinal Mucosa; Intestines; Male; Metabolism, Inborn Errors; Mutation, Missense; Receptors, Enterotoxin; Receptors, Guanylate Cyclase-Coupled; Receptors, Peptide; Sodium

A male infant with dup (1) (q32 leads to q43) constitution is reported. He had mental and physical retardation and a constellation of dysmorphisms, which are considered characteristic of trisomics for the distal one-third of the long arm of chromosome 1. The assay for guanylate kinase 1 (GUK 1) activity showed a gene dosage effect and confirmed the regional assignment of this marker in the chromosomal region indicated by data derived from somatic hybrids.

Topics: Abnormalities, Multiple; Chromosome Mapping; Chromosomes, Human, 1-3; Guanosine Monophosphate; Guanylate Kinases; Humans; Infant; Infant, Newborn; Male; Nucleoside-Phosphate Kinase; Phosphotransferases; Psychomotor Disorders; Trisomy