Chromosome Breakage for Fanconi Anemia
Test Mnemonic
CBREAK
CPT Codes
- 88249 - QTY (1)
- 88230 - QTY (1)
Performing Laboratory
Knight Diagnostic Laboratories
FDA Category
Laboratory Developed Test
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 10 mL | Whole blood | Sodium heparin (Green) | Ambient | Collect Monday through Friday only. Specimen MUST be received in the Main Campus Send Out Laboratory by noon on Fridays. |
Minimum Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 5 mL |
Stability
| Environmental Condition | Description |
|---|---|
| Ambient | 48 hours |
| Refrigerated | Unacceptable |
| Frozen | Unacceptable |
Days Performed
Mon - Sat
Turnaround Time
8 - 11 days
Methodology
| Name | Description |
|---|---|
| Stress test induced by mitomycin C (MMC) or diepoxybutane (DEB) | |
| Chromosome Analysis |
Reference Range
Special Info
Collect Monday through Friday only. Specimen MUST be received in the Send Out Laboratory by noon on Fridays. If WBC or lymphocyte percentage (%L) are below normal, please contact laboratory customer service regarding minimum specimen requirements (216-444-5755).
Clinical Info
Chromosome breakage analysis is a test for assessing genomic instability. The most common syndrome for which this test is diagnostic is Fanconi anemia (FA). FA is characterized by bone marrow failure, increased risk for cancer, and physical abnormalities. Progressive bone marrow failure is responsible for the most significant morbidity and mortality. Clinically heterogeneous, FA individuals are at increased risk for acute myelogenous leukemia, myelodysplastic syndrome, and solid tumors of the neck, head, oral cavities, and genitourinary system. Congenital abnormalities are present in approximately 70% of FA patients and include: café au lait spots or hypopigmentation; short stature; radial ray defects; eye defects such as microphthalmia; malformations of the kidney, genitalia, heart, gastrointestinal tract, ears, and feet. Currently, 21 genes have been identified that, when mutated, can cause FA or an FA-like phenotype. The first step in FA diagnosis is to perform a breakage analysis on peripheral blood. However, some FA patients undergo a self-correction of cells in the hematopoietic lineage, resulting in a normal blood breakage study. In such a case, breakage analysis of skin fibroblasts is necessary to detect the increased breakage and radial formation. This phenomenon is known as somatic mosaicism. Fibroblast breakage studies may also be preferable for patients with very low white blood cell counts.