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HelpTest Code WBGDR Beta-Globin Gene Cluster Deletion/Duplication, Blood
Specimen Required
Only orderable as a reflex. For more information see:
-HAEV1 / Hemolytic Anemia Evaluation, Blood
-HBEL1 / Hemoglobin Electrophoresis Evaluation, Blood
-MEV1 / Methemoglobinemia Evaluation, Blood
-REVE2 / Erythrocytosis Evaluation, Blood
-THEV1 / Thalassemia and Hemoglobinopathy Evaluation, Blood and Serum
Useful For
Determining the etiology of hereditary persistence of fetal hemoglobin (HPFH), delta-beta thalassemia, or other large deletions involving the beta-globin gene cluster
Diagnosing less common causes of beta-thalassemia; these large deletional beta-thalassemia alterations result in elevated hemoglobin (Hb) A2 and can have slightly elevated Hb F levels
Distinguishing homozygous Hb S disease from a compound heterozygous Hb S/large beta-globin cluster deletion disorder (ie, Hb S/beta zero thalassemia, Hb S/delta beta zero thalassemia, Hb S/HPFH, Hb S/gamma-delta-beta-thalassemia)
Diagnosing complex thalassemias where the beta-globin gene and 1 or more of the other genes in the beta-globin cluster have been deleted
Evaluating and classifying unexplained increased Hb F percentages
Evaluating microcytic neonatal anemia
Evaluating unexplained long standing microcytosis in the setting of normal iron studies and negative alpha thalassemia testing/normal Hb A2 percentages
Confirming gene fusion hemoglobin variants such as Hb Lepore and Hb P-Nilotic
Confirming homozygosity versus hemizygosity of alterations in the beta-like genes (HBB, HBD, HBG1, HBG2)
Investigating newborns with Hb A levels greater than Hb F on newborn screen in the absence of transfusion.
This test is not useful for diagnosis or confirmation of alpha thalassemia, the most common beta thalassemias, or hemoglobin variants. It also does not detect non-deletional HPFH.
Method Name
Only orderable as a reflex. For more information see:
-HAEV1 / Hemolytic Anemia Evaluation, Blood
-HBEL1 / Hemoglobin Electrophoresis Evaluation, Blood
-MEV1 / Methemoglobinemia Evaluation, Blood
-REVE2 / Erythrocytosis Evaluation, Blood
-THEV1 / Thalassemia and Hemoglobinopathy Evaluation, Blood and Serum
Polymerase Chain Reaction (PCR) Analysis/Multiplex Ligation-Dependent Probe Amplification (MLPA)
Reporting Name
Beta Globin Gene Cluster, Del/Dup,BSpecimen Type
Whole Blood EDTASpecimen Minimum Volume
2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole Blood EDTA | Refrigerated | ||
Reject Due To
No specimen should be rejected.Clinical Information
Large deletions involving the beta-globin cluster locus on chromosome 11 manifest with widely variable clinical phenotypes. Up to 10% of beta thalassemia cases (dependent on ethnicity) are caused by large deletions in the beta-globin cluster. Other thalassemias, including delta-beta thalassemia, gamma-delta-beta thalassemia, epsilon gamma thalassemia, and epsilon-gamma-delta-beta thalassemia, also result from functional loss of genes or the locus control region that controls globin gene expression. In addition, hereditary persistence of fetal hemoglobin (HPFH) is caused by deletions of variable size along the beta-globin cluster locus. Most, but not all, of the large deletion beta-globin cluster disorders are associated with variably elevated hemoglobin (Hb) F percentages that persist after 2 years of age. In addition, many manifest in microcytosis. A notable exception is HPFH, which can have normal to minimal decreased mean corpuscular volume values. The correct classification of these deletions is important as they confer variable predicted protective phenotypes, and some are more protective than others when found in combination with a second beta-globin variant, such as Hb S or beta-thalassemia. In addition, identification of these deletions can explain lifelong microcytosis in the setting of normal iron studies and negative alpha thalassemia molecular results.
Reference Values
Only orderable as a reflex. For more information see:
-HAEV1 / Hemolytic Anemia Evaluation, Blood
-HBEL1 / Hemoglobin Electrophoresis Evaluation, Blood
-MEV1 / Methemoglobinemia Evaluation, Blood
-REVE2 / Erythrocytosis Evaluation, Blood
-THEV1 / Thalassemia and Hemoglobinopathy Evaluation, Blood and Serum
An interpretive report will be provided.
Interpretation
The alterations will be provided with the classification that fits the probe pattern, if known. Further interpretation requires correlation with protein studies and red blood cell indices.
Cautions
Non-deletional subtypes of beta thalassemia or hereditary persistence of fetal hemoglobin are not detected by this assay.
Hemoglobin electrophoresis and sequencing analysis of the beta-globin gene will be performed prior to this test to exclude other diagnoses or to indicate the diagnostic utility of this testing platform.
In addition to disease-related probes, the multiplex ligation-dependent probe amplification technique utilizes probes localized to other chromosomal regions as internal controls. In certain circumstances, these control probes may detect other diseases or conditions for which this test was not specifically intended. Results of the control probes are not normally reported. However, in cases where clinically relevant information is identified, the ordering physician will be informed of the result and provided with recommendations for any appropriate follow-up testing.
Method Description
Multiplex ligation-dependent probe amplification is utilized to test for the presence of large deletions or duplications in the beta-globin cluster region.(Unpublished Mayo method)
Day(s) Performed
Wednesday, Friday
Report Available
25 to 30 daysSpecimen Retention Time
Whole blood: 2 weeks; DNA: 3 monthsPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
81363-HBB (hemoglobin, beta, beta-globin) (eg, beta thalassemia), duplication/deletion analysis
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| WBGDR | Beta Globin Gene Cluster, Del/Dup,B | 101634-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 620977 | Beta Globin Gene Cluster Del/Dup | 101634-4 |
| 620978 | Reviewed by | 18771-6 |
| 620976 | Interpretation | 69047-9 |