21-Hydroxylase Gene, CYP21A2, Full Gene Analysis, Varies
Use
This test is used for carrier screening and diagnosis of 21-hydroxylase deficient congenital adrenal hyperplasia (CAH) in individuals with personal or family history of 21-hydroxylase deficiency. It serves as a follow-up to positive CAH newborn screens and measurement of basal and adrenocorticotropic hormone-stimulated 17-hydroxyprogesterone, androstenedione, and other adrenal steroid levels. The test may identify CYP21A2 variants in individuals with a suspected diagnosis when a common variant panel is negative or only identifies one variant. It also assists in the evaluation of 21-hydroxylase deficiency in prenatal cases.
Special Instructions
This test is a molecular analysis of the CYP21A2 gene and does not include biochemical analysis of steroids. For biochemical analysis, see CAH21 / Congenital Adrenal Hyperplasia (CAH) Profile for 21-Hydroxylase Deficiency, Serum. Prenatal specimens must be accompanied by maternal blood specimens for maternal cell contamination studies.
Limitations
This test does not detect CH-2 and CH-3 TNXA::TNXB hybrids nor does it offer site-specific testing for known/familial CYP21A2 variants. The high homology between CYP21A2 and its pseudogene presents diagnostic challenges, including hybrid or chimera alleles and frequent copy number changes. Rare variants in primer binding sites can lead to allelic drop-out. Additional testing may be necessary to clarify the phase of reportable variants.
New York Approved
Methodology
PCR-based (ddPCR, MLPA, Sanger)
Biomarkers
LOINC Codes
- 94197-1
- 50397-9
- 82939-0
- 69047-9
- 48767-8
- 31208-2
- 18771-6
Result Turnaround Time
14-21 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
3 mL
Minimum Volume
Not provided
Container
Lavender top (EDTA) or yellow top (ACD)
Collection Instructions
Invert several times to mix blood. Send whole blood specimen in original tube. Do not aliquot.
Patient Preparation
A previous bone marrow transplant from an allogenic donor will interfere with testing.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 4 days |
| Refrigerated | 4 days |
| Frozen | 4 days |