Diagnosis; Risk Assessment

Establish or confirm diagnosis

Predictive risk information for patient and/or family members

Reproductive decision-making

Individuals with clinical features of 21-hydroxylase deficient congenital adrenal hyperplasia. Carrier screening and diagnosis of 21-hydroxylase deficient congenital adrenal hyperplasia (CAH) in individuals with a personal or family history of 21-hydroxylase deficiency, or as follow-up to positive CAH newborn screens and/or measurement of basal and adrenocorticotropic hormone- 1-24 stimulated 17-hydroxyprogesterone, … Individuals with clinical features of 21-hydroxylase deficient congenital adrenal hyperplasia. Carrier screening and diagnosis of 21-hydroxylase deficient congenital adrenal hyperplasia (CAH) in individuals with a personal or family history of 21-hydroxylase deficiency, or as follow-up to positive CAH newborn screens and/or measurement of basal and adrenocorticotropic hormone- 1-24 stimulated 17-hydroxyprogesterone, androstenedione, and other adrenal steroid levels. May be used to identify CYP21A2 mutations in individuals with a suspected diagnosis of 21-hydroxylase deficient CAH when a common mutation panel is negative or only identifies one mutation. View more

Is research allowed on the sample after clinical testing is complete? Help
Research testing is only performed under IRB approved protocol with an opt-out policy in place.

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 … 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) View more

Other

Tests performed
Entire test performed in-house

Accuracy and analytical sensitivity for simple variants (SNVs and INDELs): (>99%). Accuracy and specificity for del/dup detection: >99%

Because of the complexity of the genetic structure of the CYP21A2 locus, and the possibility that a patient's congenital adrenal hyperplasia (CAH) may be due to other gene defects, genetic testing results should be correlated carefully with clinical and biochemical data. This testing strategy is superior to approaches previously used, … Because of the complexity of the genetic structure of the CYP21A2 locus, and the possibility that a patient's congenital adrenal hyperplasia (CAH) may be due to other gene defects, genetic testing results should be correlated carefully with clinical and biochemical data. This testing strategy is superior to approaches previously used, but may still miss some complex and large-scale genetic rearrangements or deletions, as well as genetic changes in far upstream or downstream gene-regulatory elements that impair CYP21A2 gene expression. This can lead to false-negative test results. Rare polymorphisms in primer binding sites can lead to selective allelic drop-out, which can lead to false-negative or false-positive diagnosis. Patients without genetic evidence for disease-causing CYP21A2 genetic changes may still have CAH, but due to a different enzyme defect. Additional and expanded biochemical steroid profiling is, therefore, recommended if the clinical picture is strongly suggestive of CAH. View more

Is proficiency testing performed for this test? Help
Yes

Method used for proficiency testing: Help
Formal PT program

PT Provider: Help
American College of Medical Genetics / College of American Pathologists, ACMG/CAP

Software used to interpret novel variations Help
Variants may be analyzed using any combination of the following: Alamut, REVEL, Polyphen-2, SIFT, AGVGD, MutationTaster, SpliceSiteFinder-like, MaxEntScan, NNSPLICE, GeneSplicer, SpliceAI, gene-specific online databases, ISCA, UCSC Genome Browser

Laboratory's policy on reporting novel variations Help
All novel variants and copy number variants are evaluated for potential pathogenicity and included in the written report, accordingly.