Detection of mutations in KLHL3 and CUL3 in families with Familial Hyperkalaemic Hypertension (FHHt or Gordon Syndrome)

The study of families with rare inherited forms of hypo- and hypertension has been one of the most successful strategies to probe the molecular pathophysiology of blood pressure control and has revealed dysregulation of distal nephron sodium reabsorption to be a common mechanism. Familial Hyperkalaemic Hypertension (FHHt, Gordon Syndrome) is a salt-dependent form of hypertension caused by mutations in regulators of the thiazide-sensitive NaCl cotransporter, NCC, and is effectively treated by thiazide diuretics and/or dietary salt restriction. Variation in at least four genes can cause FHHt, including ‘With No lysine (K)’ kinases (WNK1 and WNK4), KeLcH-Like3 (KLHL3) and CULlin3 (CUL3). Here we identify novel disease-causing variants in CUL3 and KLHL3 segregating in 63% of pedigrees with previously unexplained FHHt, confirming the importance of these recently-described FHHt genes. We demonstrate conclusively, in two unrelated affected individuals, that rare intronic variants in CUL3 cause skipping of exon 9, as has been proposed. KLHL3 variants all occur in kelch-repeat domains and so are likely to disrupt WNK-complex binding. We found no evidence of plausible disease-causing variants within SLC4A8 (an alternative thiazide-sensitive sodium transporter) in this population. This supports existing evidence that CUL3 and KLHL3 gene products are physiologically important regulators of thiazide-sensitive distal nephron NaCl reabsorption, and hence potentially interest...
Source: Clinical Science - Category: Biomedical Science Authors: Source Type: research