Lab Test

Alpha Globin Gene Analysis

Alpha Globin Genotype, Alpha Thal, Alpha Thalassemia

Instructions

This test is not included in the Beaumont Laboratory testing formulary, however, the Laboratory can facilitate specimen collection.

  • This test requires pathology review. Contact the Sendout Laboratory at 248-551-9045 before ordering this test.
  • Testing requires the ordering physician to complete forms for the independent clinical laboratory performing the testing.
  • This test will be billed to the patient's insurance. If not covered by insurance, the patient is responsible for the full cost of testing.
  • Specimens received without the appropriate forms and information will not be shipped.
  • Once approved, order test as a Miscellaneous Sendout (XMISC).
  • This test is usually performed after hemoglobin electrophoresis and measurement of HbA2 to rule out beta-thalassemia.
  • Please call the Sendout Laboratory before collecting an amniotic fluid specimen. All amniotic fluid specimens must be accompanied by a maternal blood specimen. This is necessary for maternal cell contamination testing. Obtain specimen during 14th - 17th week of gestation.

Specimen Collection Criteria

Blood: Two (2) Lavender-top EDTA tube. (Minimum: 3.0 mL)

Rejection Criteria

Specimens not collected or processed as indicated.

In-Lab Processing

Deliver specimens to the Laboratory immediately after collection. Maintain blood specimens at room temperature (20-26°C or 68-78.8°F) or amniotic fluid specimens refrigerated (2-8°C or 36-46°F) until transport.

Transport: 7.0 mL whole blood, at room temperature (20-26°C or 68-78.8°F), or 10.0 mL amniotic fluid, refrigerated (2-8°C or 36-46°F). (Minimum: 3.0 mL whole blood or 5.0 mL amniotic fluid.) 

Laboratory

Sent to ILabCorp Integrated Genetic, Westbourough, MA.

Performed

Results available in 10-14 days.

Reference Range

By report.

Test Methodology

Dosage Analysis by Polymerase Chain Reaction (PCR)/Multiplex Ligation-Dependent Probe Amplification (MLPA)/Luminex Technology.

Interpretation

By report.

Hemoglobin electrophoresis should usually be done prior to this test to exclude other diagnoses or to identify non-deletion types of alpha-thalassemia.

This test is not useful for diagnosis/confirmation of beta-thalassemia or hemoglobinopathies.

Clinical Disease

Alpha-thalassemia occurs in all ethnic groups but is especially common in African Americans (30%) and in Southeast Asians (at least 25%). It is also found frequently in individuals of Mid-Eastern and Indian ancestry. While deletion type of alpha-thalassemia is much more common, both non-delection type and deletion type have been described in each affected population.

Alpha-thalassemia is caused by decreased synthesis of alpha-globin chains. Four alpha-globin genes are normally present (two on each chromosome 16). One, two, three, or four alpha-globin genes may be deleted or contain mutations in patients with alpha-thalassemia, with more than 30 alpha-haplotypes having been described. Phenotypically, these result in four categories of disease expression:

  1. Deletion of one alpha-chain results in a normal phenotype (i.e. no CBC abnormalities). 
  2. Alpha-thalassemia minor, with mild hematologic changes, but no major clinical difficulties, occurs with deletion of two alpha genes. 
  3. Hemoglobin H disease, which is extremely variable but usually includes anemia due to hemolysis, jaundice, and hepatosplenomegaly (deletion of three alpha genes) 
  4. Hydrops fetalis with deletion of all four alpha-globin genes variably results in utero demise.

CPT Codes

81257

Contacts

Last Updated

4/10/2021

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