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Inborn errors of aldosterone biosynthesis in humans
Y Shizuta1, T Kawamoto, Y Mitsuuchi
1Department of Medical Chemistry, Kochi Medical School, Nankoku, Japan.
Steroids
|January 1, 1995
Summary
Corticosterone methyl oxidase (CMO) deficiencies result from mutations in the CYP11B2 gene. CMO I deficiency is caused by a gene knockout, while CMO II deficiency involves altered enzyme activity due to specific mutations.
Area of Science:
- Endocrinology
- Molecular Genetics
- Biochemistry
Background:
- Corticosterone methyl oxidase (CMO) types I and II deficiencies are inherited disorders affecting aldosterone biosynthesis.
- Aldosterone synthase (P450aldo), encoded by CYP11B2, catalyzes the final two steps in aldosterone production.
Purpose of the Study:
- To investigate the molecular genetic basis of CMO I and CMO II deficiencies.
- To determine if mutations in the CYP11B2 gene cause both types of CMO deficiency.
Main Methods:
- Molecular genetic studies involving nucleotide sequence analysis of the CYP11B2 gene.
- Expression studies using mutant complementary DNAs (cDNAs).
Main Results:
- CMO I deficient patients have a CYP11B2 gene inactivated by a 5-bp deletion in exon 1, resulting in a complete lack of P450aldo (null mutants).
- CMO II deficient patients exhibit two point mutations in CYP11B2 (Arg181Trp and Val386Ala), leading to altered P450aldo activity (leaky mutants).
- The CYP11B1 gene is not implicated in these deficiencies.
Conclusions:
- CMO I and CMO II deficiencies are caused by distinct mutations within the CYP11B2 gene.
- These findings clarify the genetic underpinnings of aldosterone biosynthesis defects and the role of P450aldo.