Test ID: WBSEQ    
Beta Globin Gene Sequencing, Blood

Diagnosis of beta thalassemia intermedia or major

Identification of a specific beta thalassemia mutation (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

A hemoglobin electrophoresis evaluation (HBELC / Hemoglobin Electrophoresis Cascade, 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.

Beta globin gene (HBB) sequencing can be used to identify hemoglobin variants and the most common beta thalassemia mutations, including beta plus and beta zero thalassemias. It also identifies hyperunstable hemoglobin variants and dominant beta thalassemia mutations, 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 mutations and crossover events. As such, the results of this test should always be interpreted within the context of the protein studies and RBC indices.

This is a second-tier evaluation of beta thalassemia minor, intermedia, and major, as well as beta globin variant identification.

First-tier testing for beta thalassemia or beta globin variant detection is THEVP / Thalassemia and Hemoglobinopathy Evaluation or HBELC / Hemoglobin Electrophoresis Cascade, Blood.

• Thalassemia/Hemoglobinopathy Patient Information
• Informed Consent for Genetic Testing

Polymerase Chain Reaction (PCR) followed by DNA Sequence Analysis