Detection of mutations, conversions and big deletion in CYP21A2 gene

Congenital adrenal hyperplasia (CAH) is one of the most common hereditary endocrine disorders, and it is inherited in an autosomal recessive pattern. About 90-95% cases of CAH are caused by enzyme steroid 21-hydroxylase (21-OH) deficiency, due to mutations and rearrangements in CYP21A2 gene. Deficiency of this enzyme leads to decreased production of cortisol and aldosterone, and also to an increase in production of adrenal androgens. As a result of excessive androgen production and secretion, female children are affected by prenatal virilization, while both sexes are affected by accelerated growth and precocious puberty. In most severe cases, CAH can result in dehydration with electrolyte imbalance, which can lead to a fatal outcome.

Depending on severity of the symptoms, 3 forms of CAH can be distinguished: salt-wasting classical form, simple virilizing classical form, and non-classical (late onset) form. Detection of CAH causing mutations in CYP21A2 gene is useful for accurate diagnostics (distinguishing 21-OH deficiency from other CAH forms, polycystic ovary syndrome or any other disorder characterized by an elevated androgen level), optimization of treatment with hormones, and also for genetic counseling. Furthermore, molecular diagnostics is especially useful for excluding CAH in patients with low androgen excess.

Material for detection of mutations in CYP21A2 gene and CYP21A1P/CYP21A2 chimeric genes (previously designated as conversions and big deletion) is obtained by isolating DNA from the peripheral blood. Mutation detection is performed through DNA sequencing of all 10 exons and flanking intron regions of CYP21A2 gene, and detection of CYP21A1P/CYP21A2 chimeric genes is performed by allele-specific PCR.

It is necessary to deliver 2.5 ml of peripheral blood using 3.8% sodium citrate as anticoagulant in vol/vol ratio 9:1. It is possible to deliver a blood sample that has already been frozen. The samples are accepted every day from 10 to 13h. There is a possibility to deliver the sample via post express service. The analysis is performed within 15 working days. The results and the bill are sent to the patient's home address, or can be collected personally at the Institute from 10 to 16h every day.

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  • dr Maja Stojiljković
  • dr Branka Zukić
  • dr Sonja Pavlović

Tel: +381 11 3976 445

Mob: +381 65 3976 445

Fax: +381 11 3975 808


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