Hemoglobinopathy Fractionation Cascade With Reflex to α-Thalassemia
Use
Diagnose thalassemias and hemoglobin variants, with ferritin to evaluate total body storage iron, and complete blood count without differential to detect and/or identify a wide range of hematologic disorders. When appropriate, additional reflex testing will be performed for α-thalassemia. DNA analysis of the α-globulin gene locus (HBA1/HBA2 OMIM 141800 and 141850,16pter-16p13.3) can detect copy-number changes by targeting 24 different sequences in the α-globulin region, and will, in principle, detect all genomic deletions and duplications involving this locus, in addition to the Constant Spring point mutation. The mutations analyzed include Southeast Asian(--SEA), Thai(--Thai), Filipino(--FIL), Mediterranean(--MED), a3.7, and a4.2.
Special Instructions
This test is intended for adults age 20 and older. If MCV is <80 and ferritin is normal or high, testing will reflex to alpha-thalassemia DNA (α-Thalassemia Analysis [484278]). Additional charges/CPT code(s) apply if reflex testing is performed. Patients should stop biotin consumption at least 72 hours prior to sample collection due to potential interference with hemoglobinopathy fractionation.
Limitations
For ferritin, erroneous findings may occur from samples of patients treated with monoclonal mouse antibodies. Interference due to high titers of antibodies can occur, though additives minimize these effects. For reflex DNA test: does not detect germline mosaicism or large chromosomal aberrations. Results may be affected by rare genetic variants, sampling issues, or inter/intragenic interactions. False results can occur due to several factors including pseudogene interference and mislabeled samples.
Methodology
Immunoassay (ECLIA)
Biomarkers
LOINC Codes
- 12710-0
- 2276-4
- 6690-2
- 789-8
- 718-7
- 4544-3
- 787-2
- 785-6
- 786-4
- 788-0
- 777-3
- 58413-6
- 42246-9
- 20572-4
- 4552-6
- 32683-5
- 44923-1
- 44920-7
- 44922-3
- 42248-5
- 101387-9
- 12710-0
- 2276-4
- 6690-2
- 789-8
- 718-7
- 4544-3
- 787-2
- 785-6
- 786-4
- 788-0
- 777-3
- 58413-6
- 32682-7
- 20572-4
- 4552-6
- 32683-5
Result Turnaround Time
4-8 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
Three lavender-top (EDTA whole blood) tubes filled to capacity
Minimum Volume
Two lavender-top (EDTA whole blood) tubes filled to capacity
Container
Lavender-top (EDTA) tubes
Collection Instructions
Lavender-top tubes should be filled to capacity and inverted 8 to 10 times immediately after filling.
Patient Preparation
Patients should stop biotin consumption at least 72 hours prior to the collection of a sample.
Storage Instructions
Whole blood for reflex DNA test: Maintain specimen at room temperature or refrigerate at 4°C. Do not freeze.
Causes for Rejection
Hemolysis; quantity not sufficient for analysis; tube not filled with minimum fill volume; specimen drawn in anticoagulant other than EDTA; specimen diluted or contaminated with IV fluid; clotted specimen; improper labeling; transfer tubes with whole blood; lavender-top (EDTA) tubes received with plasma removed; frozen specimens
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | Serum ferritin: 14 days; whole blood CBC: 1 day; whole blood Hgb fractionation: 14 days; whole blood for reflex DNA test: 14 days |
| Refrigerated | Serum ferritin: 14 days; whole blood CBC: 3 days; whole blood Hgb fractionation: 14 days; whole blood for reflex DNA test: 30 days |
| Frozen | Serum ferritin: 14 days; whole blood CBC: unstable; whole blood Hgb fractionation: 14 days |