Diagnosis of Liddle syndrome by genetic analysis of β and γ subunits of epithelial sodium channel – a report of five affected family members

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Abstract

Objective

To screen the gene mutation in β and γ subunits of the epithelial sodium channel (ENaC) of a Chinese family, some of whose members are clinically diagnosed as suffering from Liddle syndrome.

Methods

Twelve family members were recruited to the study. Among them, two brothers had been clinically diagnosed as suffering from Liddle syndrome. Peripheral blood samples were collected from all members of the family and total genomic DNA was prepared for genetic analysis. Polymerase chain reaction (PCR) was used for amplifying the last exon of β (codon 513–673) and γ (codon 503–632) subunits of the ENaC gene. PCR products were purified and subjected to a direct DNA sequence analysis.

Results

Genetic analysis of the βENaC gene revealed a missense mutation of CCC to CTC at codon 616 in four middle-aged men of the second generation and one young woman of the third generation. There was no mutation of the γENaC gene in any of the individuals examined.

Conclusion

Through direct DNA sequencing analysis, we diagnosed the disease present in five members of a Chinese family as Liddle syndrome, and excluded it in some other young offspring suffering from the monogenic disease. Our results provide further evidence that Pro616 is a critical amino acid that has a key role in the inhibition of sodium channel activity.

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