Congenital Adrenal Hyperplasia (CAH) Confirmatory Testing with CAH RealFast™ CNV Assay

Congenital Adrenal Hyperplasia (CAH) encompasses metabolic disorders that lead to inadequate synthesis of adrenal steroid hormones, such as cortisol and aldosterone. The most common form of CAH is associated with genetic variants in the CYP21A2 gene, which encodes steroid 21-hydroxylase. CAH can manifest with a range of clinical presentations, from virilization of female newborns to life-threatening salt-wasting conditions.

The Challenge of CAH Diagnosis

To address CAH, newborn screening programs based on 17-hydroxyprogesterone (17-OHP) levels have been implemented worldwide. However, the high false-positive rate of 17-OHP assays necessitates second-tier testing for confirmation, often through liquid chromatography-tandem mass spectroscopy or molecular genetic analysis.

Principle of the Test

The assay relies on the fluorogenic 5’ nuclease assay (TaqMan® assay). Each reaction contains gene-specific primer pairs for amplifying CYP21A2 and the EC gene. Dual-labeled hydrolysis probes, one labeled with FAM for CYP21A2 and the other with HEX for the EC gene, hybridize to internal sequences of the amplified fragments. During PCR, the Taq DNA polymerase cleaves the 5’-fluorescent reporter from the hybridized probe, generating a real-time fluorescent signal proportional to the PCR product. The assay is a relative quantitation method, comparing the amount of nucleic acid targets to the CAH CNV Calibrator.

In conclusion, ViennaLab’s CAH RealFast™ CNV Assay offers a fast, accurate, and cost-efficient solution for detecting CYP21A2 gene copy number variations, a critical component of CAH diagnosis. Healthcare professionals can confidently use this assay to ensure timely and effective patient care.