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HelpOrder Code WBSEQ Beta Globin Gene Sequencing, Varies
Useful For
Diagnosis of beta thalassemia intermedia or major
Identification of a specific beta thalassemia sequence variant (ie, unusually severe beta thalassemia trait)
Evaluation of an abnormal hemoglobin electrophoresis identifying a rare beta-globin variant
Evaluation of chronic hemolytic anemia of unknown etiology
Evaluation of hereditary erythrocytosis with left-shifted p50 oxygen dissociation results
Preconception screening when there is a concern for a beta-hemoglobin disorder based on family history
Genetics Test Information
Beta-globin gene (HBB) sequencing can be used to identify hemoglobin variants and the most common beta thalassemia sequence variants, including beta plus and beta zero thalassemias. It also identifies hyper-unstable hemoglobin variants and dominant beta thalassemia sequence variants, as well as other hemoglobin variants that cannot be identified by protein methods. Some hemoglobin disorders will not be detected by beta-globin gene sequencing, such as large deletional alterations and crossover events. As such, the results of this test should always be interpreted within the context of the protein studies and red blood cell indices.
Testing Algorithm
A hemoglobin electrophoresis evaluation (HBEL1 / Hemoglobin Electrophoresis Evaluation, Blood) is always indicated prior to beta-globin gene sequencing because these conditions can be complex and protein data allows accurate and rapid classification of the patient phenotype.
Special Instructions
Method Name
Polymerase Chain Reaction (PCR)/Sanger Sequencing
Reporting Name
Beta Globin Gene Sequencing, BSpecimen Type
VariesOrdering Guidance
For first-tier testing for beta thalassemia, order THEV1 / Thalassemia and Hemoglobinopathy Evaluation, Blood and Serum.
For first-tier testing for beta-globin variant detection, order HBEL1 / Hemoglobin Electrophoresis Evaluation, Blood.
Necessary Information
1. Patient's age is required.
2. Include recent transfusion information.
Specimen Required
Specimen Type: Whole blood
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable:Â Yellow top (ACD), green top (sodium heparin)
Specimen Volume: 4 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send whole blood specimen in the original tube. Do not aliquot.
Specimen Stability Information: Refrigerate 30 days(preferred)/Ambient 14 days
Specimen Type: Extracted DNA from whole blood
Container/Tube: 1.5- to 2-mL tube
Specimen Volume: Entire specimen
Collection Instructions:
1. Label specimen as extracted DNA and source of specimen
2. Provide volume and concentration of the DNA
Specimen Stability Information:Â Frozen (preferred)/Refrigerate/Ambient
Specimen Minimum Volume
Blood: 1 mL; Extracted DNA: 50 mcL at 50 ng/mcL concentration
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Varies | ||
Reject Due To
| Moderately to severely clotted | Reject |
Reference Values
An interpretive report will be provided.
Method Description
Genomic DNA is extracted from whole blood. The HBB gene is amplified by polymerase chain reaction (PCR). The PCR product is then purified and sequenced in both directions using fluorescent dye-terminator chemistry. Sequencing products are separated on an automated sequencer and trace files analyzed for variations in all exons, introns with the exception of IVS-II-82 through IVS-II-650, the 5'UTR, the 3'UTR, and the promoter region. Results are correlated with routine studies to identify unusual beta globin variants.(Reddy PL, Bowie LJ. Sequence-based diagnosis of hemoglobinopathies in the clinical laboratory. Clin Lab Med. 1997;17[1]:85-96; Traeger-Synodinos J, Harteveld CL. Advances in technologies for screening and diagnosis of hemoglobinopathies. Biomarkers Med. 2014;8[1]:115-127)
Day(s) Performed
Monday through Friday
Performing Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
81364-HBB (hemoglobin, beta) full sequence
Forms
1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available:
-Informed Consent for Genetic Testing (T576)
-Informed Consent for Genetic Testing-Spanish (T826)
2. Metabolic Hematology Patient Information (T810)
3. If not ordering electronically, complete, print, and send a Benign Hematology Test Request (T755) with the specimen.