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


Ordering Guidance


 



Additional Testing Requirements


Hemoglobin electrophoresis studies performed at Mayo Clinic Laboratories are highly recommended prior to this test to allow for more complete interpretation of results. See HBEL1 / Hemoglobin Electrophoresis Evaluation, Blood or THEV1 / Thalassemia and Hemoglobinopathy Evaluation, Blood and Serum.



Shipping Instructions


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



Necessary Information


Metabolic Hematology Patient Information (T810) is required; see Special Instructions. Send a completed form with the specimen. Document the reason for suspecting a large beta cluster locus deletion along with the hemoglobin F percentage and red blood cell indices for the patient.



Specimen Required


Specimen Type: Whole 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 whole blood specimen in the original tube. Do not aliquot.

Specimen Stability Information: Refrigerated: 30 days; Ambient: 8 hours


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. If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

Metabolic Hematology Patient Information (T810) is required.

Benign Hematology Test Request (T755)

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 variants result in elevated hemoglobin (Hb) A2 and usually have slightly elevated HbF levels

 

Distinguishing homozygous Hb S disease from a compound heterozygous HbS/large beta-globin cluster deletion disorder (ie, HbS/beta zero thalassemia, Hb S/delta-beta zero thalassemia, HbS/HPFH, HbS/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 HbF percentages

 

Evaluating microcytic neonatal anemia

 

Evaluating unexplained long standing microcytosis in the setting of normal iron studies and negative alpha thalassemia testing/normal HbA2 percentages

 

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

 

Confirming homozygosity vs hemizygosity of variants 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 HPFH.

Genetics Test Information

This test can be used to identify a variety of conditions (see Highlights) that involve large deletions of the beta-globin gene cluster. These alterations will not be detected by DNA sequencing of the beta-globin gene.

Testing Algorithm

A hemoglobin electrophoresis evaluation (HBEL1 / Hemoglobin Electrophoresis Evaluation, Blood) is always indicated prior to beta-globin cluster locus deletion and duplication testing as these conditions can be complex and protein data allows accurate classification of the patient phenotype.

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

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Reference Values

An interpretive report will be provided.

Method Description

Multiplex ligation-dependent probe amplification (MLPA) is utilized to test for the presence of large deletions in the beta-globin gene.(Unpublished Mayo method)

Day(s) Performed

Wednesday, Friday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

81363-HBB (hemoglobin, beta, beta-globin) (eg, beta thalassemia), duplication/deletion analysis