Identification of a single cytosine base insertion mutation at Arg-597 of the beta subunit of the human epithelial sodium channel in a family with Liddle's disease.

Abstract

We describe a family with Liddle's disease caused by a novel mutation of the beta subunit of the human epithelial sodium channel (ENaC). A 15-year-old Japanese female was referred to our outclinic because of hypertension. The physical examination showed no abnormal findings except mild hypertension, but the laboratory data revealed low levels of plasma renin activity, plasma aldosterone and serum potassium. A comprehensive analysis of steroid hormones showed only high levels of urinary free cortisol and 17-hydroxycorticosteroids. During loading tests, blood pressure and serum potassium responded well to triamterene and slightly to spironolactone, but did not respond to dexamethasone. In addition, the normal ratio of tetrahydrocortisol plus 5alpha-tetrahydrocortisol to tetrahydrocortisone in a 24 h urinary excretion test strongly suggested a diagnosis of Liddle's disease rather than apparent mineralocorticoid excess syndrome. DNA sequence analysis of members of this family revealed a single cytosine base insertion at Arg-597 of the beta human ENaC in the proband and her mother, leading to a loss of the last 34 amino acids from the normally encoded protein as the result of a frameshift. We conclude that a de novo cytosine insertion into the final exon of the C-terminus of the beta human ENaC is responsible for Liddle's disease in this Japanese family.

• Authors: T Inoue, Y Okauchi, Y Matsuzaki, K Kuwajima, H Kondo, N Horiuchi, K Nakao, M Iwata, Y Yokogoshi, Y Shintani, H Bando, S Saito
• Journal: European journal of endocrinology (Eur J Endocrinol) Vol. 138 Issue 6 Pg. 691-7 (Jun 1998) ISSN: 0804-4643 [Print] England
• PMID: 9678538 (Publication Type: Case Reports, Journal Article, Review)

Chemical References

• Peptide Fragments
• Sodium Channels
• Cytosine
• Arginine

Topics

• Adolescent
• Adult
• Amino Acid Sequence
• Amino Acid Substitution
• Arginine
• Base Sequence
• Cytosine
• Epithelial Cells (physiology)
• Female
• Genes, Dominant
• Humans
• Hypertension (blood, genetics)
• Molecular Sequence Data
• Mutagenesis, Insertional
• Pedigree
• Peptide Fragments (genetics)
• Sodium Channels (chemistry, genetics)
• Syndrome
• Water-Electrolyte Imbalance (genetics)