Test Documentation
Alpha-Globin Gene Deletion or Duplication

Specimen Required
Draw blood in a lavender EDTA tube. Send 10.0 mL whole blood (4.0 mL minimum) at room temperature. Specimen stability is crucial. Store and ship at room temperature immediately.

Alternate Specimen
Whole blood:   Sodium heparin (green-top)  
   Lithium heparin (green-top)  
   ACD solution B (yellow-top)  
Cultured cells: T-25 Flask (call laboratory for sample requirements)
Chorionic villus sampling: Tissue culture media (call laboratory for sample requirements)

Rejection Criteria
Sample received frozen.

Multiplex PCR, Capillary Electrophoresis

Room temperature: 8 days; Refrigerated: 8 days; Frozen: Unacceptable

Reference Range
Alpha-Globin Del/Duplicat (UOM)
Alpha-globin is an essential component of the hemoglobin tetramer, beginning in the early stages of embryonic development. Deletion mutations involving one or both of the alpha-globin genes (designated HBA1 (alpha-1) and HBA2 (alpha-2)) in the alpha-globin gene cluster (located on chromosome 16p13) lead to reduced production of alpha-globin chains, and are the major cause of alpha-thalassemia. The severity of symptoms is dependent on the number of functional alpha-globin genes remaining.
In the assay, multiplex-polymerase chain reaction (PCR) amplification of fragments specific for the 5'-end, interior, and 3'-end of the alpha1- and alpha2-globin genes is carried out in the presence of fluorescently-labeled primers. In addition, fragments representing the HS40/locus control region (LCR), the alpha-globin pseudogene, as well 3 non-alpha globin fragments used as internal controls, are co-amplified. Amplification products are analyzed on an automated capillary DNA sequencer.
This assay cannot detect single nuclotide substitutions and small insertion/deletion mutations in the alpha-globin gene cluster. Since genetic variation and other factors can affect the accuracy of direct mutation testing, the results of this testing should always be interpreted in light of clinical and familial data. For assistance with the interpretation of the results, please contact your local Quest Diagnostics genetic counselor or call 1-866-Geneinfo (436-3463).
This test was developed and its performance characteristics have been determined by Quest Diagnostics Nichols Institute, San Juan Capistrano. Performance characteristics refer to the analytical performance of the test.
Note: Results from this assay are not useful for carrier determination. Carriers ususally have levels in the normal range.

Sets up 1 day a week. (am)

Turnaround TimeReports in 20 days
Test CodeAGDEL
CPT-4 Code (s)