Genetic diagnosis of Liddle's syndrome by mutation analysis of SCNN1B and SCNN1G in a Chinese family.

Background: Liddle's syndrome is a rare autosomal-dominant monogenic form of salt-sensitive hypertension. This study aimed to screen the gene mutation in β and γ subunits of the epithelial sodium channel (ENaC) of a Chinese family with Liddle's syndrome, an autosomal dominant form of hypertension.

Methods: DNA samples from the proband with early-onset, treatment-resistant hypertension and suppressed plasma renin activity were initially screened for mutations in the C-terminal exons of the ENaC β or γ subunit genes, using amplification by polymerase chain reaction and direct DNA sequencing. We also screened the C-terminus of SCNN1B and SCNN1G in family members, and screened for the mutation in 150 controls.

Results: Genetic analysis of the β ENaC gene revealed a missense mutation of CCC to TCC at codon 616 in the proband, her mother and her grandmother. One hundred and fifty randomly selected controls had not the mutation, indicating that this is not a common genetic polymorphism. There was no mutation of the γ ENaC gene in any of the individuals examined.

Conclusions: Through direct DNA sequencing analysis, we established the diagnosis of Liddle's syndrome for the proband and her families, and provided tailored therapies to this abnormality. These results provide further evidence that Pro616Ser is a critical amino acid that has a key role in the inhibition of sodium channel activity.