ARUP's Laboratory Test Directory
| 0051495: Alpha Thalassemia, HBA1 & HBA2 Gene Deletions |
![[ image for: Patient History for Hemoglobinopathy]](icon_39.jpg){kind=icon} | Patient History for Hemoglobinopathy |
| Test Mnemonic: ALPHA THAL | |
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Methodology: Polymerase Chain Reaction/Gel Electrophoresis
Performed: Mon, Thu Reported: 7-10 days |
| Specimen Required: | |
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Collect: One 3 mL lavender (EDTA) or pink (K2EDTA).
Transport: 3 mL whole blood at 2-8°C. (Min: 1 mL) Pediatric Collection/Transport: 1 mL whole blood at 2-8°C. Stability: Ambient: 3 days; Refrigerated: 1 week; Frozen: Unacceptable |
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| Reference Interval: |
| By report |
| Interpretive Data: | |
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Background Information: Characteristics: Alpha (+) thalassemia (silent carrier): Mutation of a single alpha2 globin gene (-a/aa); asymptomatic. Alpha (0) thalassemia (trait): Mutation of both alpha2 globin genes, or deletion of alpha1 and alpha2 globin genes in cis (-a/-a; --/aa); mild microcytic anemia possible. Hemoglobin H disease: Mutation of three alpha globin genes (--/-a); hemolysis with Heinz bodies, moderate anemia, splenomegaly. Hb Bart Hydrops Fetalis Syndrome: Mutation of four alpha globin genes (--/--); lethal in fetal or early neonatal period. Incidence: Carrier frequency in Mediterranean (1:30-50), Middle Eastern, Southeast Asian (1:20), African, African-American (1:3). Inheritance: Autosomal recessive. Cause: Mutations in the alpha globin gene cluster 95% are deletions. Mutations Tested: -a3.7, -a4.2, -(a)20.5, --SEA, --MED, --FIL, --THAI Clinical Sensitivity: Varies by ethnicity, may be as high as 90%. Methodology: Polymerase chain reaction and gel electrophoresis. Analytical Sensitivity and Specificity: Greater than 99% Limitations: Rare alpha globin gene deletions, non-deletion mutations, gene duplications, and mutations of the regulatory region will not be detected. Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com. Please refer to Statement C in the Compliance Statements section in the front of the Laboratory Test Directory. |
| CPT Code(s): | |
| 83890 Isolation; 83900 Amplification multiplex; 83901 x8 Additional amplification; 83894 Gel separation; 83912 Interpretation and report - Additional CPT code modifiers may be required for procedures performed to test for oncologic or inherited disorders. |