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Test Code WBDD Beta-Globin Cluster Locus, Deletion/Duplication, Varies


Advisory Information


 



Additional Testing Requirements


Hemoglobin electrophoresis studies performed at Mayo Clinic are highly recommended prior to this test to allow for more complete interpretation of results. See HBELC / Hemoglobin Electrophoresis Cascade, Blood or THEVP / Thalassemia and Hemoglobinopathy Evaluation.



Shipping Instructions


Specimens must arrive within 4 days (96 hours) of collection.



Specimen Required


Specimen Type: Peripheral blood

Collection Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Yellow top (ACD)

Specimen Volume: 4 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send specimen in the original tube.

Specimen Stability Information: Refrigerated (preferred)/Ambient


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 in Special Instructions:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Complete, print and send a Thalassemia/Hemoglobinopathy Patient Information sheet (T358) with the specimen (in Special Instructions). Document the reason for suspecting a large beta cluster locus deletion along with the Hb F percentage and RBC indices for the patient.

Useful For

Determining the etiology of hereditary persistence of fetal hemoglobin (HPFH), or delta-beta-thalassemia

 

Diagnosing less common causes of beta-thalassemia; these large deletional beta-thalassemia mutations result in elevated hemoglobin (Hb) A2 and usually 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 one 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 vs hemizygosity of mutations in the beta-like genes (HBB, HBD, HBG1, HBG2)

 

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 nondeletional hereditary persistence of fetal hemoglobin.

Testing Algorithm

This test is recommended to identify a variety of conditions involving large deletions or duplications within the beta-globin gene cluster locus region including:

-Identifying large deletions causing increased hemoglobin (Hb) F levels such as hereditary persistence of fetal hemoglobin (HPFH), delta-beta-thalassemias, and gamma-delta-beta-thalassemia

-Identifying beta-thalassemia conditions in cases where beta gene sequencing did not find a beta-thalassemia mutation

-Confirming gene fusion hemoglobin variants such as Hb Lepore and Hb P-Nilotic

-Investigating newborns with unexplained microcytic anemia that is suspected to be caused by epsilon-gamma-delta-beta-thalassemia

-Confirming homozygosity vs hemizygosity of mutations in the beta-like genes (HBB, HBD, HBG1, HBG2)

-Investigating individuals older than 12 months of age with unexplained microcytosis and normal hemoglobin electrophoresis for whom more common causes of microcytosis such as iron deficiency and alpha-thalassemia have been excluded

Method Name

Polymerase Chain Reaction (PCR) Analysis/Multiplex Ligation-Dependent Probe Amplification (MLPA)

Reporting Name

Beta Globin Cluster Locus Del/Dup

Specimen Type

Varies

Specimen Minimum Volume

2 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Varies

Reject Due To

No specimen should be rejected.

Reference Values

An interpretive report will be provided.

Day(s) and Time(s) Performed

Wednesday; 10 a.m., Friday; 2 p.m.

Performing 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. This test has not been cleared or approved by the U.S. 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
WBDD Beta Globin Cluster Locus Del/Dup In Process

 

Result ID Test Result Name Result LOINC Value
48361 Beta Globin Cluster Locus Del/Dup 50397-9
48438 Specimen 31208-2
48360 Reviewed by 18771-6
48362 Interpretation 69047-9