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Order Code WAGDR Alpha Globin Cluster Locus Deletion/Duplication, Blood


Ordering Guidance


Sequence variants, other than the alpha T-Saudi and hemoglobin Constant Spring alterations, are not detected by this assay. For detection of single point and other nondeletion variants, order WASEQ / Alpha Globin Gene Sequencing, Varies, if clinically indicated.



Specimen Required


Patient Preparation: A previous bone marrow transplant from an allogeneic donor will interfere with testing. For instructions for testing patients who have received a bone marrow transplant, call 800-533-1710.

 

Specimen Type: Whole blood

Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Yellow top (ACD)

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send whole blood specimen in original tube. Do not aliquot.


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. Molecular Genetics: Congenital Inherited Diseases Patient Information (T521)

Useful For

Diagnosis of alpha-thalassemia

 

Carrier screening for individuals from high-risk populations for alpha-thalassemia

 

This test is not useful for diagnosis or confirmation of beta-thalassemia or hemoglobinopathies.

Genetics Test Information

This test is for genetic deletions and duplications only.

Method Name

Dosage Analysis by Polymerase Chain Reaction (PCR)/Quantitative Polymerase Chain Reaction (qPCR)/Multiplex Ligation-Dependent Probe Amplification (MLPA)

Reporting Name

Alpha Globin Clustr Locus Del/Dup,B

Specimen Type

Varies

Specimen Minimum Volume

Blood: 1 mL

Specimen Stability Information

Specimen Type Temperature Time
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

This test is a direct variant analysis assay. Deletions and duplications within the alpha-globin locus are identified by a multiplex ligation-dependent probe amplification assay. Thirty-three probes that hybridize throughout the alpha-globin locus from the HS40 promoter region through the 3'HVR region are utilized in order to maximize the information needed to map the approximate location of nearly all DNA deletions that occur. A quantitative polymerase chain reaction-based assay is used to detect the presence of hemoglobin Constant Spring (HBA2: c.427T >C) and alphaT-Saudi (HBA2: c.*94A>G) point mutations. In addition, a polymerase chain reaction-based assay is used to detect the presence of the alpha-3.7 and alpha-4.2 deletions.(Schouten JP, McElgunn CJ, Waaijer R, Zwijnenburg D, Diepvens F, Pals G. Relative quantification of 40 nucleic acid sequences by multiplex ligation-dependent probe amplification. Nucleic Acids Res. 2002;30[12]:e57. doi:10.1093/nar/gnf056)

Day(s) Performed

Varies

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

81269