Cytogenetic Testing in Multiple Myeloma

Hello. My name is Dr. Beth Faiman. Welcome to the Multiple Myeloma Center for Nurses.

In this video we’ll review the cytogenetic changes that frequently occur in patients with multiple myeloma and cover some of the tests used to detect them.

Genetic analysis of malignant plasma cells provides important prognostic information. This information helps evaluate the evolution of monoclonal gammopathy of undetermined significance, or MGUS, to active myeloma, helps determine risk stratification, and may guide treatment decisions for myeloma patients.¹

Cytogenetics is a type of genetic analysis that focuses on the study of chromosomes and chromosomal abnormalities.²

Chromosomal abnormalities are found in as many as 90% of patients newly diagnosed with myeloma.³

Accordingly, the International Myeloma Working Group (or IMWG) suggests that, at minimum, cytogenetic testing should include the following chromosomal abnormalities⁴:
• t(4;14)
• t(11;14)
• t(14;16)
• t(14;20)
• del(17p13)
• del(13)
• Chromosome 1 abnormalities

Because chromosomal changes such as these play such an important role in the development and prognosis of multiple myeloma, it is important to understand the tests we use to determine the genotypes of a patient’s disease.

Cytogenetic information is used for:
• Stratifying patients’ disease into low-, standard-, intermediate-, or high-risk categories; and^1,5,6
• Staging disease according to IMWG guidelines⁵

The tests we will discuss in this video are performed using a sample obtained through a bone marrow biopsy and aspiration.^7,8 The aspirate is the liquid portion of the biopsy. A number of tests can be performed on bone marrow aspirate that are helpful in evaluating a patient’s disease.

These include cytogenetic tests such as karyotyping and fluorescence in situ hybridization, also called FISH.^7,8

Let’s take a closer look at these 2 tests.

An image or photo of chromosomes is called a karyotype.⁹

A normal karyotype consists of 46 individual chromosomes: 22 pairs of autosomes and 1 pair of sex chromosomes.¹⁰

Each of these chromosomes consists of 2 short “p” arms and 2 long “q” arms. The center where the arms intersect is referred to as the centromere.¹⁰

Pathologists use a banding technique to ascertain patterns in the chromosomes. This helps them to visualize the number, arrangement, size, and structure of chromosomes.⁹

Some of the abnormalities we see in a karyotype can include translocations, numerical abnormalities, deletions, and inversions.¹¹

A translocation occurs when pieces of chromosomes swap places.¹¹ One example is a t(4;14) translocation, meaning portions of the 4th and 14th chromosome have swapped genetic information. More or fewer than the normal 46 chromosomes is called aneuploidy.¹² Examples are trisomy, where there are 3 copies of a chromosome instead of 2, and monosomy, where there is only 1 copy of a chromosome.¹²

Another example of a frequently seen chromosomal abnormality is a deletion, where a portion of a chromosome is lost.¹² An example of this would be reported as a del(17p13) abnormality, meaning that the “p” arm of the 17th chromosome is missing or is deleted.

A duplication occurs when part of the chromosome is copied too many times. An inversion occurs when the chromosome breaks in 2 places. The resulting piece of DNA is reversed and then reinserted into the chromosome.¹¹

An abnormal karyotype may contain multiple abnormalities. An example of a karyotype can be seen here with additions, deletions, and translocations. The numbers beside the chromosomes denote the origin of translocated material.¹³

While cytogenetic analysis by conventional karyotyping detects chromosomal abnormalities in plasma cells,^13,14 FISH is a laboratory technique that detects and locates specific DNA sequences on chromosomes.¹⁵

FISH has been shown to be more sensitive than conventional karyotyping in identifying chromosomal translocations.⁷

In fact, national and international guidelines suggest that all patients undergo genetic analysis by FISH for determination of stage and risk assessment.^16,17 The FISH technique uses fluorescent labeling to see where a specific gene falls within an individual chromosomes.¹⁵

Unlike other techniques used to study chromosomes, FISH is not performed on actively dividing cells.¹⁵ In this test, a chromosome is exposed to a small DNA sequence probe tagged with a fluorescent molecule. The probe binds to its complementary pairs on the chromosome and because it is fluorescent, the DNA sequence of interest can be easily visualized.¹⁵

The output of FISH is a single cell with specific DNA sequences illuminated. The positions of the sequences and the overlap are important aspects of the analysis.¹⁸

In this example, the plasma cell on the right shows distinct red and green signals indicative of a translocation. By comparison, the cell on the left shows no evidence of a translocation.¹⁸

Three other cytogenetic assays are currently being investigated and incorporated into use in academic centers:
Plasma cell labeling index to quantify the proliferative activity of the malignant clone⁷
Single nucleotide polymorphism, or SNP, arrays to match genes and/or chromosomes associated with different prognoses,¹⁹ and
Gene expression profiling, or GEP, to help determine molecular subgroups and risk status in a timeframe that will allow treatment to be modified accordingly²⁰

This concludes the Cytogenetic Testing in Multiple Myeloma video. To find out more on this and other topics related to multiple myeloma, please see additional videos and resources on this site.

Here you will also find a number of educational tools to help you discuss these topics with your patients, answers to common questions, and other downloadable materials.

Thank you.

References:
1. Rajan AM, Rajkumar SV. Interpretation of cytogenetic results in multiple myeloma for clinical practice. Blood. 2015:5:e365.
2. National Cancer Institute. Cytogenetics. http://www.cancer.gov/dictionary?cdrid=270737. Accessed September 28, 2019.
3. Avet-Loiseau H, Attal M, Moreau P, et al. Genetic abnormalities and survival in multiple myeloma: the experience of the Intergroupe Francophone du Myélome. Blood. 2007;109(8):3489-3495.
4. Palumbo A, Rajkumar SV, San Miguel JF, et al. International Myeloma Working Group consensus statement for the management, treatment, and supportive care of patients with myeloma not eligible for standard autologous stem-cell transplantation. J Clin Oncol. 2014;32(6):587-600.
5. Chng WJ, Dispenzieri A, Chim CS, et al. IMWG consensus on risk stratification in multiple myeloma. Leukemia. 2014;28(2):269-277.
6. Mikhael JR, Dingli D, Roy V, et al. Management of newly diagnosed symptomatic multiple myeloma: updated Mayo Stratification of Myeloma and Risk-Adapted Therapy (mSMART) consensus guidelines 2013. Mayo Clin Proc. 2013;88(4):360-376.
7. Mangan PA. Patient assessment. In: Tariman JD. Multiple Myeloma: A Textbook for Nurses. Pittsburgh, PA: ONS Publishing Division; 2012:55‐75.
8. American Cancer Society. Signs and symptoms of multiple myeloma. http://www.cancer.org/cancer/multiplemyeloma/detailedguide/multiple-myeloma-testing. Accessed September 28, 2019.
9. National Institutes of Health. Karyotyping. https://medlineplus.gov/ency/article/003935.htm. Accessed September 28, 2019.
10. National Institutes of Health. Genetics Home Reference. How do geneticists indicate the location of a gene?
https://ghr.nlm.nih.gov/primer/howgeneswork/genelocation. Accessed September 28, 2019.
11. National Institutes of Health. Genetics Home Reference. Can changes in the structure of chromosomes affect health and development? https://ghr.nlm.nih.gov/primer/mutationsanddisorders/structuralchanges. Accessed September 28, 2019.
12. National Institutes of Health. Genetics Home Reference. Can changes in the number of chromosomes affect health and development? https://ghr.nlm.nih.gov/primer/mutationsanddisorders/chromosomalconditions. Accessed September 28, 2019.
13. Sawyer JR, Lukacs JL, Munshi N, et al. Identification of new nonrandom translocations in multiple myeloma with multicolor spectral karyotyping. Blood. 1998;92(11):4269‐4278.
14. Multiple Myeloma Research Foundation. Diagnostic tests. https://www.themmrf.org/multiple-myeloma/diagnosis/myeloma-diagnostic-testing/. Accessed September 28, 2019.
15. National Institutes of Health. Fluorescence in situ hybridization (FISH). http://www.genome.gov/10000206. Accessed June 20, 2016.
16. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines). Multiple myeloma. Version 2.2020. https://www.nccn.org/professionals/physician_gls/pdf/myeloma.pdf. Published September 2019.
17. Engelhardt M, Terpos E, Kleber M, et al; for the European Myeloma Network. European Myeloma Network recommendations on the evaluation and treatment of newly diagnosed patients with multiple myeloma. Haematologica. 2014;99(2):232-242.
18. Fonseca R, Blood EA, Oken MM, et al. Myeloma and the t(11;14)(q13;q32); evidence for a biologically defined unique subset of patients. Blood. 2002;99(10):3735‐3741.
19. Avet‐Loiseau H, Li C, Magrangeas F, et al. Prognostic significance of copy‐number alterations in multiple myeloma. J Clin Oncol. 2009;27(27):4585‐4590.
20. Weinhold N, Heuck C, Rosenthal A, et al. The clinical value of molecular subtyping multiple myeloma using gene expression profiling. Leukemia. 2016;30(2):423-430.