Liddle'S Syndrome With A Clinical Phenotype Mimicking Essential Hypertension

Objective: Liddle's syndrome (LS) is a monogenic form of hypertension due to mutations of either β or γ subunits of the epithelial sodium channel (ENaC). We have previously reported a novel mutation (βP617L) of ENaC, resulting in the typical phenotype of LS, which includes hypokalemic alkalosis. Functional expression of this mutant ENaC showed a three-fold increase in the amiloride-sensitive Na+ current. Aim of this study was to analyze the clinical and biochemical phenotype of a second family carrying the βP617L mutation. Subjects and Methods: Both direct sequencing and restriction enzyme digestion of the C-terminal exon of the SCNN1B gene were performed in the proband, in the proband's parents and in the members of the maternal line who consented to the analysis. Results: The proband, a 21 year-old male, had been hypertensive since the age of 17 ys. Early onset hypertension characterized 7 members of the maternal line across 3 generations. βP617L mutation was detected in all available members with juvenile hypertension. Proband's maternal kindred was of Sicilian origin, as was the family carrying the same mutation previously reported by our group, despite no apparent relationship between them. Pretreatment clinical findings in the proband and the other analyzed carriers of the mutation are shown in the Table.Conclusion: Measurement of both renin and aldosterone is worth performing in all patients with early onset hypertension, independently of serum potassium level, in order to exclude monogenic forms of low-renin hypertension. The incidence of LS may be greater than is currently thought.