Beta Globin Gene Sequencing, Varies

Casandra

Casandra Test Code MC57718Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID WBSEQCPT Code 81364

Beta Globin Gene Sequencing, Varies

Clinical Use

Use

Beta-globin gene sequencing is useful in the evaluation of beta-globin chain variants and beta thalassemia. It detects almost all beta-globin variants and the most common beta thalassemia sequence variants, although prevalence is ethnicity dependent. Because these conditions are often complex, this test should always be interpreted in the context of protein studies, such as hemoglobin electrophoresis and red blood cell indices. The majority of beta-globin chain variants are clinically and hematologically benign; however, some have important clinical consequences, such as erythrocytosis, cyanosis/hypoxia, chronic hemolysis, or unexplained microcytosis.

Special Instructions

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.

Limitations

This assay will not detect large deletions or duplications within the beta globin gene. In addition, hybrid beta globin variants (i.e., hemoglobin Lepore) will not be detected by this method. This method cannot distinguish between homozygous and compound heterozygous variants associated with large deletions. This method cannot distinguish between double substitution on a single chromosome and a compound heterozygous state. Beta-globin sequencing alone is not able to distinguish between alterations that are found in the same copy of the HBB gene (i.e., variants that are 'linked' or 'in cis') and alterations found on different HBB gene copies (i.e., are 'in trans').

Test Details

New York Approved