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Test ID: CMAH Chromosomal Microarray, Hematologic Disorders, Varies

Useful For

Detection and characterization of clonal copy number imbalance and loss of heterozygosity associated with hematologic neoplasms

 

Assisting in the diagnosis and classification of certain hematologic neoplasms

 

Evaluating the prognosis for patients with certain hematologic neoplasms

Testing Algorithm

DNA extraction is always performed on the specimen prior to hybridization to the microarray. An unstimulated cell culture will be set up on all specimens with adequate volume and held pending additional testing. If additional testing is requested, such as karyotype analysis or FISH, it will be performed at an additional charge.

 

This test is not appropriate for detecting constitutional/congenital copy number changes or regions of excessive homozygosity. If this test is ordered with a reason for referral indicating a constitutional/congenital disorder, the test will be cancelled and CMACB / Chromosomal Microarray, Congenital, Blood will be performed as the appropriate test.

 

The following algorithms are available in Special Instructions:

-Aggressive B-cell Lymphoma Diagnostic Algorithm in Special Instructions

-B-Lymphoblastic Leukemia/Lymphoma Algorithm

Method Name

Chromosomal Microarray (CMA) Using Applied Biosystems (Affymetrix) Cytoscan HD

Reporting Name

Chromosomal Microarray, Hematologic

Specimen Type

Varies


Necessary Information


1. A reason for referral must be provided for testing to be performed.

2. A pathology report should accompany the specimen. If this information is not available at the time of order, submit as soon as possible for appropriateness of testing and to aid in interpretation of results.



Specimen Required


Provide a reason for referral with each specimen. The laboratory will not reject testing if this information is not provided, but appropriate testing and interpretation may be compromised or delayed.

 

Submit only 1 of the following specimens:

 

Specimen Type: Bone marrow
Container/Tube: Green top (sodium heparin)
Specimen Volume: 1-2 mL
Collection Instructions:
1. Invert several times to mix bone marrow.
2. If sodium heparin is not available, EDTA is acceptable.

 

Specimen Type: Whole blood
Container/Tube: Green top (sodium heparin)
Specimen Volume: 7-10 mL
Collection Instructions:
1. Invert several times to mix blood.
2. If sodium heparin is not available, EDTA is acceptable.


Specimen Minimum Volume

Blood: 2 mL
Bone Marrow: 1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Ambient (preferred)
  Refrigerated 

Clinical Information

The importance of identifying chromosome abnormalities in hematologic disorders is well established, and often provides important diagnostic, prognostic, and therapeutic information critical to proper patient management. Although many chromosomal abnormalities are large enough to be detected with conventional chromosome analysis, many others are below its limits of resolution, and conventional chromosome analysis does not detect copy-neutral loss of heterozygosity. 

           

Chromosomal microarray (CMA) improves the diagnostic yield to identify genetic changes that are not detected by conventional chromosome analysis or FISH studies. CMA utilizes >1.9 million copy number probes and approximately 750,000 single nucleotide polymorphism probes to detect copy number changes and regions of copy-neutral loss of heterozygosity.

                                      

CMA analysis is appropriate to identify gain or loss of chromosome material throughout the genome at a resolution of 30 to 60 kilobases. CMA can do the following:

-Define the size, precise breakpoints, and gene content of copy number changes to demonstrate the complexity of abnormalities

-Characterize unidentified chromosome material, marker chromosomes, and DNA amplification detected by conventional chromosome and FISH studies

-Determine if apparently balanced chromosome rearrangements identified by conventional chromosome studies have cryptic imbalances

-Assess regions of copy-neutral loss of heterozygosity, which is common in neoplasia and often masks homozygous mutations involving tumor suppressor genes

 

The limit of detection is dependent on size of the abnormality, type of abnormality (deletion or duplication) and DNA quality. When a deletion or duplication exceeds the reporting limits, mosaicism can confidently be detected as low as 25% and may be lower if the abnormality is large and DNA quality is good.

Reference Values

An interpretive report will be provided.

Interpretation

The interpretive report describes copy number changes and any loss of heterozygosity that may be associated with the neoplastic process. Abnormal clones with subclonal cytogenetic evolution will be discussed if identified.

           

The continual discovery of novel copy number variation and published clinical reports means that the interpretation of any given copy number change may evolve with increased scientific understanding.

 

Although the presence of a clonal abnormality usually indicates a neoplasia, in some situations it may reflect a benign or constitutional genetic change. If a genetic change is identified that is likely constitutional and clearly pathogenic (eg, XYY), follow-up with a medical genetics consultation may be suggested.

 

The absence of an abnormal clone may be the result of specimen collection from a site that is not involved in the neoplasm, or may indicate that the disorder is caused by a point mutation that is not detectable by chromosomal microarray (CMA).

 

CMA, FISH, and conventional cytogenetics are to some extent complementary methods. In some instances, additional FISH or conventional cytogenetic studies will be recommended to clarify interpretive uncertainties.

Clinical Reference

1. Cooley L, Lebo M, Li M, et al: American College of Medical Genetics and Genomics technical standards and guidelines: microarray analysis for chromosome abnormalities in neoplastic disorders. Genet Med 2013;15:484-494

2. Dougherty M, Wilmoth D, Tooke L, et al: Implementation of high resolution single nucleotide polymorphism array analysis as a clinical test for patients with hematologic malignancies. Cancer Genetics 2011;204:26-38

3. Schwartz, S: Clinical Utility of Single Nucleotide Polymorphism Arrays. Clin Lab Med 2011;31:581-594

4. Braggio E, Kay N, VanWier S, et al: Longitudinal genome-wide analysis of patients with chronic lymphocytic leukemia reveals complex evolution of clonal architecture at disease progression and at the time of relapse. Leukemia 2012;26:1698-1701

Day(s) and Time(s) Performed

Specimens are processed Monday through Sunday.

Results reported Monday through Friday, 8 a.m.-5 p.m.

Analytic Time

8 days

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

81277

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CMAH Chromosomal Microarray, Hematologic 94087-4

 

Result ID Test Result Name Result LOINC Value
54721 Result Summary 50397-9
54722 Result 62356-1
54723 Nomenclature 62378-5
54724 Interpretation 69965-2
CG902 Reason For Referral 42349-1
CG903 Specimen 31208-2
54725 Source 31208-2
54726 Method 49549-9
53423 Additional Information 48767-8
54727 Released By 18771-6

Forms

If not ordering electronically, complete, print, and send a Hematopathology/Cytogenetics Test Request (T726) with the specimen. 

Mayo Clinic Laboratories | Hematology Catalog Additional Information:

mml-acute-leukemia-myelodysplastic-syndromes, mml-myeloproliferative-neoplasm, mml-lymphoid-disorders