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Test ID: THEV1 Thalassemia and Hemoglobinopathy Evaluation, Blood and Serum


Necessary Information


Include recent transfusion information.

 

Include most recent complete blood cell count results.

 

Include ferritin results if not sending serum

 

Metabolic Hematology Patient Information (T810) is strongly recommended. Testing may proceed without this information, however if the information requested is received, any pertinent reported clinical features and data will drive the focus of the evaluation and be considered in the interpretation.

 

The laboratory has extensive experience in hemoglobin variant identification and many cases can be confidently classified without molecular testing. However, molecular confirmation is always available, subject to sufficient sample quantity (eg, MLPA testing requires at least 2 mLs of sample in addition to protein testing requirements). If no molecular testing or specific molecular tests are desired, utilize the appropriate check boxes on the form. If the form or other communication is not received, the reviewing hematopathologist will select appropriate tests to sufficiently explain the protein findings which may or may not include molecular testing.



Specimen Required


Blood and serum are required.

 

Specimen Type: Whole blood

Container/Tube: Lavender top (EDTA)

Specimen Volume: 15 mL

Collection Instructions: Send specimen in original tube. Do not aliquot.

 

Specimen Type: Serum

Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.6 mL

Collection Instructions:

1. Serum gel tubes should be centrifuged within 2 hours of collection.

2. Red-top tubes should be centrifuged and the serum aliquoted into a plastic vial within 2 hours of collection.

3. Label specimen as serum.


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. Metabolic Hematology Patient Information (T810) in Special Instructions

Useful For

Evaluation of microcytosis

 

Extensive and economical diagnosis and classification of hemoglobinopathies or thalassemia including complex disorders

 

Diagnosis of hereditary persistence of hemoglobin (HPFH)

Profile Information

Test ID Reporting Name Available Separately Always Performed
THEVI Hemoglobinopathy Interpretation No Yes
HGBCE Hb Variant, A2 and F Quantitation,B Yes Yes
HPLC HPLC Hb Variant, B No Yes
FERR Ferritin, S Yes Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
HPFH Hb F Distribution, B No No
SDEX Sickle Solubility, B Yes No
IEF Isoelectric Focusing, B No No
UNHB Hb Stability, B No No
MASS Hb Variant by Mass Spec, B No No
ATHAL Alpha-Globin Gene Analysis Yes No
WASQR Alpha Globin Gene Sequencing, B Yes, (Order WASEQ) No
WBSQR Beta Globin Gene Sequencing, B Yes, (Order WBSEQ) No
WBDDR Beta Globin Cluster Locus Del/Dup,B Yes, (Order WBDD) No
WGSQR Gamma Globin Full Gene Sequencing No No
THEV0 Thalassemia Summary Interpretation No No

Testing Algorithm

This is a consultative evaluation in which the case will be evaluated at Mayo Clinic Laboratories, the appropriate tests performed at an additional charge, and the results interpreted.

 

This evaluation will always include hemoglobins A(2) and F and hemoglobin electrophoresis utilizing cation exchange high-performance liquid chromatography (HPLC) and capillary electrophoresis methods.

 

If a serum sample is received, a serum ferritin will always be performed to allow incorporation of possible iron deficiency into profile interpretation and economical test utilization. If the ferritin component is not desired, do not send a serum sample and none will be performed or charged. Note: If a ferritin is not performed or provided, and if microcytosis is present and no other abnormalities are found (beta thalassemia, a hemoglobin variant that is associated with microcytosis), the case will be reflexed to alpha-globin gene analysis unless otherwise requested not to be performed.

 

Hemoglobin electrophoresis reflex testing, performed at additional charge, may include any or all of the following as indicated to identify rare hemoglobin variants present: sickle solubility (hemoglobin S screen), hemoglobin heat and isopropanol stability studies (unstable hemoglobin), isoelectric focusing, Hb F distribution by flow cytometry (hemoglobin F red cell distribution), cation exchange HPLC, DNA (Sanger) testing for beta chain variants and the most common beta thalassemias (beta-globin gene sequencing), multiplex ligation-dependent probe amplification (MLPA) testing for beta cluster locus large deletions and duplications, including large deletional hereditary persistence of fetal hemoglobin (HPFH), delta-beta (DBT), delta thalassemias, gamma-delta-beta (GDBT), and epsilon-gamma-delta-beta (EGDBT) thalassemias (beta globin cluster locus del/dup), large deletional alpha thalassemias and alpha gene duplications (alpha-globin gene analysis), alpha chain variants and non-deletional alpha thalassemias (alpha-globin gene sequencing), and gamma chain variants and non-deletional HPFH (gamma-globin full gene sequencing).

 

An additional consultative interpretation that summarizes all testing will be provided after test completion to incorporate subsequent results into overall evaluation if any of the following molecular tests are reflexed on the Thalassemia and Hemoglobinopathy Evaluation.

-ATHAL / Alpha-Globin Gene Analysis, Varies

-WASQR / Alpha-Globin Gene Sequencing, Blood

-WBSQR / Beta-Globin Gene Sequencing, Blood

-WBDDR / Beta-Globin Cluster Locus Deletion/Duplication, Blood

-WGSQR / Gamma-Globin Full Gene Sequencing, Varies

The results of the individual protein and molecular tests will be released as they are completed; with a final summary interpretation report correlating all performed testing with any clinical information or complete blood cell count results received.

 

See Benign Hematology Evaluation Comparison in Special Instructions.

Method Name

THEVI: Consultative Interpretation

HGBCE: Capillary Electrophoresis

HPLC: Cation Exchange/High-Performance Liquid Chromatography (HPLC)

FERR: Immunoenzymatic Assay

IEF: Electrophoresis

MASS: Mass Spectrometry (MS)

HPFH: Flow Cytometry

UNHB: Isopropanol and Heat Stability

THEV0: Medical Interpretation

Reporting Name

Thalassemia and Hemoglobinopathy Ev

Specimen Type

Serum
Whole Blood EDTA

Specimen Minimum Volume

Blood: 2.5 mL
Serum: 0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated 7 days
Whole Blood EDTA Refrigerated 7 days

Clinical Information

This consultative study is primarily designed for the evaluation of microcytosis but also has the ability to test for the detection of almost all known hemoglobin disorders in an economical manner. Because this can include multiple tests for alpha-thalassemias, beta-thalassemias, delta-beta-thalassemia, hereditary persistence of fetal hemoglobin (HPFH), and for all known hemoglobin (Hb) variants, an expert in these disorders can guide testing to explain the clinical question or reported complete blood cell count values. This evaluation is particularly useful for complete classification of compound combinations of Hb S with alpha- or beta-thalassemia, Hb E/beta-0-thalassemia, and many other complex alpha and beta thalassemia disorders. Since iron deficiency can mimic thalassemias, ferritin levels are measured to evaluate this possibility, if a serum sample is received.

 

Hb disorders include those associated with thalassemias (decreased protein quantity) and Hb variants (abnormal protein production). Many are clinically harmless and others cause symptoms including microcytosis, sickling disorders, hemolysis, erythrocytosis, cyanosis/hypoxia, long-standing or familial anemia, compensated or episodic anemia, and increased methemoglobin or sulfhemoglobin results. Hb disorders can show patterns of either autosomal recessive or autosomal dominant inheritance.

 

The thalassemias are a group of disorders of Hb synthesis. Normal adult Hb consists of 2 alpha globin chains (encoded by 2 pairs of alpha globin genes, each pair located on chromosome 16), and 2 beta globin chains (encoded by 2 beta globin genes, each located on chromosome 11). Thalassemia syndromes result from an underproduction of 1 or 2 types of globin chains and are characterized by the type (alpha, beta, delta, gamma) and magnitude of underproduction (number of defective genes) and the severity of clinical symptoms (minor, intermedia, major). The severity of the clinical and hematologic effects is directly related to the imbalance of alpha-like to beta-like chains.

 

The most common form of thalassemia is alpha thalassemia. Alpha thalassemia usually involves deletion of entire alpha genes, and varies in severity depending on the number of alpha chains deleted (or rendered nonfunctional). Alpha thalassemia trait usually results from the deletion of two alpha genes. The most common form of Hb H disease, results from dysfunction of 3 alpha chains, and shows a variable phenotype with most showing moderate anemia. The deletion of all 4 alpha genes (Barts hydrops fetalis) is incompatible with life without significant medical intervention. Non-deletional alpha thalassemia alterations can also result in either thalassemia trait or Hb H disease and are less common than deletional forms.

 

Conversely most beta thalassemia alterations are due to single nucleotide substitutions that can occur anywhere in the beta globin gene. Large deletions of the beta globin gene complex can result in elevations in Hb F, such as hereditary persistence of fetal hemoglobin (HPFH) or delta-beta thalassemia. While the presence of a single beta gene variants (beta thalassemia trait) results primarily in red blood cells (RBC) microcytosis, cases with two beta gene abnormalities show a wide range in clinical severity, and many cases require molecular testing to understand the phenotype.

Reference Values

Definitive results and an interpretive report will be provided.

Interpretation

A hematopathologist expert in these disorders evaluates the case, appropriate tests are performed, and an interpretive report is issued.

Clinical Reference

1. Hoyer JD, Hoffman DR: The thalassemia and hemoglobinopathy syndromes. In: McClatchey KD, Amin HM, Curry JL, eds. Clinical Laboratory Medicine. 2nd ed. Lippencott Williams and Wilkins; 2002: 866-892

2. Brancaleoni V, Di Pierro E, Motta I, Cappellini MD: Laboratory diagnosis of thalassemia. Int J Lab Hematol. 2016; 38 (Suppl 1):32-40

3. Hartveld C: State of the art and new developments in molecular diagnostics for hemoglobinopathies in multiethnic societies. Int J Lab Hematol. 2013; 36:1-12

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

83020-26-Hemoglobinopathy Interpretation

83020-Hb Variant, A2 and F Quantitation

83021-HPLC Hb Variant

82728-Ferritin

82664 (if appropriate)

83068 (if appropriate)

83789 (if appropriate)

88184 (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
THEV1 Thalassemia and Hemoglobinopathy Ev In Process

 

Result ID Test Result Name Result LOINC Value
FERR Ferritin, S 20567-4
41927 Hb A 20572-4
65615 HPLC Hb Variant, B No LOINC Needed
608425 Hemoglobinopathy Interpretation 14869-2
608868 Reviewed By 18771-6
41928 Hb F 4576-5
41929 Hb A2 4551-8
41930 Variant 1 24469-9
41931 Variant 2 24469-9
41932 Variant 3 24469-9
41933 HGBCE Interpretation 78748-1
Mayo Clinic Laboratories | Hematology Catalog Additional Information:

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