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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
Chromosome Analysis, DEB Assay for Fanconi Anemia
Test CodeCPT Codes
88230, 88249
Physician Attestation of Informed Consent
Preferred Specimen
Infants: 3 mL whole blood collected in a pediatric (3 mL) vacutainer
Minimum Volume
Other Acceptable Specimens
Instructions
Clinical history and reason for referral are required with test order.
Specimen viability decreases during transit. Send specimen to testing lab for viability determination. Do not freeze. Do not reject.
This test may be canceled and replaced by: Chromosome Analysis, Blood, No Growth, if the specimen does not yield mitotically active cells for analysis; or with a Cytogenetics Communication, if a communication is required.
Transport Temperature
Specimen Stability
Refrigerated: See Collection Instructions
Frozen: See Collection Instructions
Methodology
Chromosome Breakage (DEB) • Tissue Culture
Setup Schedule
Limitations
Reference Range
Clinical Significance
This assay is a first-line screening test for patients with clinical suspicion of Fanconi anemia, an inherited disorder that causes chromosomal instability [1]. This test is not used to evaluate carrier status for Fanconi anemia or for prenatal testing.
Fanconi anemia is a multigenic and primarily autosomal recessive disorder caused by pathogenic variants that affect DNA repair. Populations with increased carrier frequencies for 1 or more of these pathogenic variants include individuals of Ashkenazi Jewish, Afrikaner, sub-Saharan African, Roma, or South Asian (Indian and Pakistan) descent [1]. Clinical manifestations of Fanconi anemia vary broadly and may include congenital abnormalities, bone marrow failure, predisposition to cancer, and severe toxicity to chemotherapy. Early diagnosis is critical for patient management, especially in severe cases [1].
This test evaluates chromosome breakage in cultured lymphocytes following treatment with diepoxybutane (DEB), a DNA cross-linking agent. Lymphocytes from patients with Fanconi anemia typically have an increased number of chromosomal breaks and aberrations. Clinical care guidelines for Fanconi anemia indicate that a positive test result should be followed by genetic testing to identify pathogenic variants; a negative test result with weak clinical suspicion may not require further testing; and an indeterminate (equivocal) result may be confirmed with a skin fibroblast chromosome breakage test [1].
Although chromosome breakage analysis performed with peripheral blood is considered the gold standard for laboratory diagnosis of Fanconi anemia [1], other rare chromosome breakage disorders can also cause positive results. These include Nijmegen breakage syndrome, Roberts syndrome, and Warsaw breakage syndrome.
The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.
Reference
1. Sroka I, et al, eds. Fanconi Anemia Clinical Care Guidelines. 5th ed. Fanconi Anemia Research Fund; 2020. Accessed April 19, 2022. https://www.fanconi.org/images/uploads/other/Fanconi_Anemia_Clinical_Care_Guidelines_5thEdition_web.pdf
Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153