SLC26A3 and congenital chloride diarrhoea.

Congenital chloride diarrhoea (CLD, OMIM214700) is a rare genetic disease caused by mutations in a plasma membrane protein, the solute-linked carrier family 26 member A3 (SLC26A3) protein, which encodes for an epithelial anion exchanger for Cl- and HCO3-. The main clinical symptom is a lifetime watery diarrhoea with a high Cl- content and low pH, causing dehydration and hypochloremic metabolic alkalosis. CLD may be fatal, if not adequately treated by substitution of NaCl, KCl and fluid lost in the faeces. Long-term prognosis is generally favourable, but complications such as renal disease, inflammatory bowel disease, hyperuricemia, inguinal hernias, spermatoceles and male subfertility are possible. The role of dysfunctional SLC26A3 in the pathogenesis of these complications is poorly known. Altogether 30 different mutations of the SLC26A3 gene are currently known among patients with CLD; the most common of them being the three founder mutations present among Finns (V317del), Polish (I675676ins) and Arabic (G187X) populations. Individual variation in the clinical picture of CLD is common, but not known to associate with the genotype.