Test Catalog

Test ID: CYPZ    
21-Hydroxylase Gene (CYP21A2), Full Gene Analysis, Varies

Method Description Describes how the test is performed and provides a method-specific reference

A combined testing approach involving PCR amplification, bi-directional sequence analysis, and multiplex ligation-dependent probe amplification (MLPA) is used to identify sequence variants and copy number variation within the CYP21A2 gene (GenBank accession number NM_000500; build GRCh37 (hg19)).


Four sets of PCR primer pairs amplify the CYP21A2 gene, the inactive CYP21A1P pseudogene, and the CYP21A2/CYP21A1P and CYP21A1P/CYP21A2 hybrids to determine the presence or absence of amplification product.


Bi-directional full gene sequence analysis, including a portion of the promoter and 3-prime untranslated regions, is then performed on the CYP21A2 gene and the CYP21A2/CYP21A1P hybrid (if present) to test for the presence of sequence variants. Because the CYP21A1P/CYP21A2 hybrid and the CYP21A1P pseudogene are expected to be inactive, sequencing is not performed unless required for interpretation.


MLPA is performed to determine the copy number of the 5-prime and 3-prime regions of the CYP21A2 gene and the CYP21A1P pseudogene. Quantification and comparison of results is used to determine the copy number of the CYP21A2 gene, the CYP21A1P pseudogene, the CYP21A2/CYP21A1P and CYP21A1P/CYP21A2 hybrids. Correlation of results from PCR, bi-directional sequencing, and MLPA is used to determine the CYP21A2 genotype.


This technology cannot always determine the cis/trans status (cis=same chromosome, trans=opposite chromosomes) of the identified genes, rearrangements, or mutations. Family studies of blood relatives might assist in determination of the cis/trans status.(Cradic KW, Grebe SK: A diagnostic sequencing assay for Cyp21 based on promoter activity provides better understanding of gene rearrangements. Abstract. Endocrine Society Annual Meeting, ENDO 2005)

PDF Report Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.


Report Available The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

14 to 21 days

Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

Whole Blood: 2 weeks (if available) Extracted DNA: 3 months

Performing Laboratory Location Indicates the location of the laboratory that performs the test