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Mutation THR-185 ILE is associated with corticosterone methyl oxidase deficiency type II
1Department of Paediatrics, Christian-Albrechts-University of Kiel, Germany. m.peter@pediatrics.uni-kiel.de
Insights
Genetic analysis identified a Thr185Ile mutation in the CYP11B2 gene in a patient with corticosterone methyl oxidase (CMO) deficiency type II. This mutation likely reduces enzyme activity, causing salt-loss and hyperkalaemia.
Area of Science:
- Endocrinology
- Molecular Genetics
- Pediatric Medicine
Background:
- Corticosterone methyl oxidase (CMO) deficiency type II is a rare genetic disorder.
- It is characterized by life-threatening salt-loss and hyperkalaemia, often triggered by infection.
- Diagnosis is typically based on plasma and urinary steroid profiles.
Observation:
- A molecular genetic study was performed on one of two previously reported boys with CMO deficiency type II.
- The patient exhibited an elevated plasma 18-hydroxycorticosterone/aldosterone ratio, a key indicator of CMO deficiency type II.
- Sequence analysis of the CYP11B2 gene was conducted.
Findings:
- A homozygous single base exchange in codon 185 of the CYP11B2 gene was identified.
- This genetic alteration resulted in a Thr185Ile amino acid substitution.
- The identified mutation was found in the patient diagnosed with CMO deficiency type II.
Implications:
- The Thr185Ile mutation in the CYP11B2 gene is associated with CMO deficiency type II.
- This mutation may alter the enzyme's secondary structure, leading to decreased activity.
- Understanding the molecular basis of CMO deficiency type II can inform diagnosis and potential therapeutic strategies.
Unlabelled:
Two boys presenting with infection-triggered, life-threatening salt-loss and hyperkalaemia were published in 1991 in the European Journal of Pediatrics. In both boys, the diagnosis of corticosterone methyl oxidase (CMO) deficiency type II has been established on the basis of determinations of plasma and urinary steroids. We had the opportunity to perform a molecular genetic study in one of the two boys. This boy had an elevated plasma 18-hydroxycorticosterone/aldosterone ratio which is pathognomonic for CMO deficiency type II. Sequence analysis of the CYP11B2 gene revealed a homozygous single base exchange in codon 185 of CYP11B2 causing an amino acid substitution Thr185Ile.
Conclusion:
A Thr185Ile mutation in the CYP11B2 gene was found in a patient with CMO deficiency type II. This mutation may change the secondary structure of the enzyme leading to its decreased activity.