[A study of mutation(s) of the epithelial sodium channel gene in a Liddle's syndrome family].

OBJECTIVE

To study the genetic mechanism of Liddle's syndrome in a family and help the diagnosis (specially ante-natal) and treatment of Liddle's syndrome clinically.

METHODS

(1) Physical examination and measurement of serum potassium, plasma aldosterone and renin activity respectively by biochemical and radioimmunological assays were made for the member of the family. (2) Venous blood samples were collected from the members of the family and total genomic DNA was prepared. One set of specific primers was used for direct polymerase chain reaction, for amplifying C terminus of beta-subunit of epithelial sodium channel (hbetaENaC). Polymerase chain reaction products were subjected to single-strand conformation polymorphism and direct DNA sequence analysis.

RESULTS

A new frameshift mutation (1bp, INS, 600G) of the gene of C terminus of beta-subunit of hbetaENaC was found in the Liddle's syndrome family. This mutation introduced a new stop codon at position 605 and deleted the last 34 normal amino acids from the C teminus of hbeta ENaC. Eight genetically affected subjects had severe hypertension and suppressed levels of plasma aldosterone and plasma renin activity; half of them had hypokalemia.

CONCLUSION

The frameshift mutation (1bp, INS, 600G) of hbetaENaC gene is the likely cause of Liddle's syndrome in this Chinese family.