Molecular confirmation of a suspected structural hemoglobinopathy or beta thalassemia.
Polymerase Chain Reaction/Sequencing
Lavender (EDTA) or pink (K2EDTA). Also acceptable: Yellow (ACD Solution A or B).
Transport 3 mL whole blood. (Min: 1 mL)
Ambient: 1 week; Refrigerated: 1 month; Frozen: 6 months
Normal: This specimen has a normal sequence of the b-globin gene. No variants were identified within the b-globin coding region, the intron/exon splice site boundaries or intronic positions IVS-II 654, IVS-II 705, and IVS-II 745. Gene deletions or variants causing thalassemias or hemoglobinopathies outside of these regions will not be identified.
Background Information: Beta Globin (HBB) Sequencing
Characteristics: Structural hemoglobinopathies or thalassemias (insufficient or absent beta-chain production).
Incidence: Varies with ethnicity.
Inheritance: Usually autosomal recessive, infrequently autosomal dominant.
Cause: Pathogenic variants in the HBB gene.
Variants tested: The complete protein coding sequence with exon/intron boundaries, 5'proximal promoter and untranslated region, 3' polyadenylation signal, and intronic variants c.93-21 (IVS-I-110), c.316-197 (IVS-II-654), c.316-146 (IVS-II-705), c.316-106 (IVS-II-745), and c.316-86_316-85 (IVS-II-765 L1).
Clinical Sensitivity: Up to 97 percent, depending upon ethnicity.
Methodology: Bidirectional sequencing of the HBB coding regions, intron-exon boundaries, 5' proximal promoter and untranslated region, 3'polyadenylation signal, and intronic variants c.93-21 (IVS-I-110), c.316-197 (IVS-II-654), c.316-146 (IVS-II-705), c.316-106 (IVS-II-745), and c.316-86_316-85 (IVS-II-765 L1).
Analytical sensitivity: 99 percent.
Limitations: Diagnostic errors can occur due to rare sequence variations. Large deletions, and variants in distal regulatory elements are not detected.
Compliance Statement C: For human genetic inheritable conditions and mutations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|0050578||Beta Globin Full Gene Sequencing||21689-5|
- HBB mutation testing, B Globin gene