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Genotype-phenotype associations in non-classical steroid 21-hydroxylase deficiency
N Weintrob1, C Brautbar, A Pertzelan
1Institute for Endocrinology and Diabetes, Schneider Children's Medical Center of Israel, Petah Tiqva and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
European Journal of Endocrinology
|October 7, 2000
Summary
Genotype differences in steroid 21-hydroxylase deficiency (21-OHD) correlate with clinical variability. Compound heterozygotes with one mild and one severe mutation show earlier puberty and more precocious puberty, suggesting enzyme defect severity influences pubertal timing.
Area of Science:
- Endocrinology
- Genetics
- Pediatric Endocrinology
Background:
- Non-classical steroid 21-hydroxylase deficiency (NC21-OHD) presents with variable clinical manifestations.
- Genetic mutations in the steroid 21-hydroxylase (CYP21) gene are known causes of 21-OHD.
Purpose of the Study:
- To investigate if CYP21 gene mutations explain clinical variability in NC21-OHD.
- To determine the relationship between genotype and ethnic origin in Israeli Jewish patients.
- To correlate genotype with clinical phenotype and hormone levels.
Main Methods:
- Genotyping for CYP21 mutations in 45 Israeli Jewish patients with NC21-OHD.
- Classification of patients into groups based on mutation severity (homozygous mild, compound heterozygous mild/severe, single mild mutation).
- Comparison of clinical and hormonal data between genotype groups, focusing on compound heterozygotes for mild and severe mutations.
Main Results:
- Compound heterozygotes for one mild and one severe mutation (Group B) presented younger, with greater height and advanced bone age SDS.
- Group B exhibited significantly higher peak 17-hydroxyprogesterone (17-OHP) levels post-ACTH stimulation.
- Earlier pubarche, gonadarche, and a higher incidence of precocious puberty were observed in Group B compared to those with only mild mutations.
Conclusions:
- CYP21 genotype is a significant factor contributing to the phenotypic variability of NC21-OHD.
- The severity of the enzymatic defect, particularly compound heterozygosity for mild and severe mutations, influences the timing and pattern of puberty.
- Genotype-phenotype correlations aid in understanding the spectrum of NC21-OHD presentation.