Two novel mutations of the CYP11B2 gene in a Japanese patient with aldosterone deficiency type 1

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 596-623-Case Reports: Pediatric Endocrinology & Metabolism
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-597
Toshihiro Tajima*1, Akie Nakamura2, Katsura Ishizu3, Keiko Homma4 and Tomonobu Hasegawa5
1Hokkaido Univ Sch of Med, Hokkaido, Japan, 2Hokkaido University School of Medicine, Sapporo, Japan, 3Hokkaido Univ Schl of Med, Sapporo-Shi, Japan, 4Keio Univ Sch of Medicine, Nishitokyo-Shi, Japan, 5Keio Univ Sch of Medicine, Tokyo, Japan
Isolated hypoaldosteronism is a rare and occasionally life-threatening cause of salt wasting in infancy. A 2-month-old Japanese boy of unrelated parents was examined for failure to thrive and poor weight gain. Laboratory findings were hyponatremia, hyperkalemia, high plasma renin and low aldosterone levels. Spot urine analysis by gas chromatography-mass spectrometry (GC-MS) showed that urinary excretion of corticosterone metabolites was elevated. Whereas excretion of 18-hydroxycortricostetone metabolites was within the normal range, excretion of aldosterone metabolites was undetectable. The patient was therefore suspected to have aldosterone synthase deficiency type 1. Sequence analysis of CYP11B2, the gene encoding aldosterone synthase (CYP11B2), showed that the patient was a compound heterozygote for c.168G>A, p.W56X in exon 1 and c.1149C>T, p.R384X in exon 7. p.W56X was inherited from his mother and p.R384X was from his father. Since both alleles contain nonsense mutations, a lack of CYP11B2 activity was speculated to cause his condition

To our knowledge, this is the first Japanese patient in which the molecular basis of aldosterone synthase deficiency type 1 has been clarified. This case also indicates that spot urinary steroid analysis is useful for diagnosis.

Nothing to Disclose: TT, AN, KI, KH, TH

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