The Frequency of CYP 21 Gene Mutations in Turkish Women with Hyperandrogenism

Abstract

Objective: The congenital adrenal hyperplasias (CAH) are a group of autosomal recessive disorders due to decreased activity of the enzymes responsible for cortisol biosynthesis. Since CYP21 gene mutations in non-classical CAH (NC-CAH) due to 21-hydroxylase deficiency among Turkish women have not been well characterized, we performed CYP21 genotype analyses to determine the frequency of specific mutations in our population.

Design: Clinical study in women with hyperandrogenism at Endocrinology Department of a University Hospital. The CYP21 genotype analysis was performed at the Children's Hospital of Pittsburgh.

Patients and Methods: The study population included 32 Turkish women with hyperandrogenism and hirsutism, 5 patients with NC-CAH due to 21-hydroxylase deficiency and their 3 first degree relatives. The following steroids were measured: cortisol, prolactin, DHEAS, free testosterone, testosterone, LH, FSH, estradiol, 17-OHP, 11-deoxycortisol, and androstenedione. The ACTH stimulation test was performed in the follicular phase of the menstrual cycle. CYP21 mutations were detected by CYP21 specific PCR followed by allele specific restriction fragment length polymorphism (RFLP) or single strand conformational polymorphism analyses.

Results: Among hirsute Turkish women with hyperandrogenemia 21.9% was heterozygous carriers of CYP21 mutations; all had basal and stimulated 17-OHP values within the normal range. Alleles detected were as follows: Q318X, V281L, del/gene conversion, and R356W. Thus, 21.9% of women were heterozygous CYP21 carriers.

Conclusion: The frequency of CYP21 heterozygosity is high among Turkish women with hirsutism and hyperandrogenism. Women with hyperandrogenism who are heterozygous CYP21 mutation carriers have normal basal and stimulated 17-OHP levels. In other words, normal basal and ACTH-stimulated 17-OHP responses do not exclude heterozygosity for CYP21 mutations. The molecular differences between symptomatic carriers, e.g., our patients and asymptomatic CYP21 mutations carriers, e.g., mothers of children with classical CAH, remain to be elucidated.

Key words

21-hydroxylase deficiency - CYP 21 gene - hyperandrogenism

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