Background: Liddle syndrome is an autosomal dominant form of salt-sensitive hypertension caused by mutations in the epithelial sodium channel expressed in the distal nephron playing an essential role in Na absorption. All reported mutations in Liddle syndrome are either missense mutations or frameshift mutations destroying the PY motif closer to the C-terminus of the beta or gamma subunits causing the situation that the epithelial sodium channels are not degraded and sodium is pooled and thus hypertension and hypokalemia are caused.
Methods: We sequenced the C-terminus of the beta or gamma subunits of the epithelial sodium channel in a Japanese family of a patient clinically diagnosed as having Liddle syndrome.
Results: As a result, we found in the proband, a frameshift mutation of the beta subunit caused by a single cytosine insertion at the codon 595, introducing a new stop codon at 605 and deleting the last 34 amino acids from the normally encoded protein.
Conclusion: This mutation is carried by neither parent (with paternity proven) and hence confirms this has occurred as a event within this family.