Understanding Chromosomal Changes in CLL/SLL Cells2
CLL/SLL cells can have chromosomal deletions (part of a chromosome lost or deleted), gene mutations (change), or a combination of both.
- Parts of a chromosome can be lost (deleted) during cell division. Chromosomal deletions are named “del” for “deletion” followed by the name of the missing piece.
- Genes can become mutated (changed). Some mutations may cause cancer, but not all mutations are dangerous.
Gene mutations and chromosomal deletions can affect how CLL/SLL progresses and may change your treatment plan.
How will my doctor know of chromosomal abnormalities in my CLL/SLL cells?1,2
One of the tests known to search for chromosomal deletions is FISH. FISH stands for “fluorescence in situ hybridization.” Chromosomal deletions are written as “del” followed by the part of the chromosome that is deleted—for example, del 17p and del 11q. A different lab test, called DNA sequencing, examines CLL/SLL cells for gene mutations. It can identify the mutational status of IGHV (immunoglobulin heavy-chain variable region gene) and other genes.
What might my test results mean?1,4,5
Your test results may help you and your doctor better understand your disease. More than 50% of patients with CLL/SLL have a sign of high-risk disease that can inform how their disease will progress. To learn more about genetic testing, contact your doctor.
Some genetic risk factors for CLL/SLL are:
- This chromosomal deletion indicates that CLL/SLL may be more severe compared to people with a complete chromosome.
- Among people with CLL/SLL who have not had any treatment, approximately 1 in 10 have the 17p chromosome deletion. Del 17p can become more common as CLL progresses.
- Another chromosomal deletion that can mean that CLL/SLL may be more severe than in people with a complete chromosome.
- About 1 in 5 people with CLL have 11q deletion.
- The unmutated IGHV gene is a risk factor linked to more aggressive disease.
- Approximately 1 in 2 people with CLL have unmutated IGHV.
- Leukemia & Lymphoma Society. Chronic lymphocytic leukemia. https://www.lls.org/content/nationalcontent/resourcecenter/freeeducationmaterials/leukemia/pdf/cll.pdf. Accessed April 10, 2019.
- National Comprehensive Cancer Network. NCCN Guidelines for Patients®: Chronic lymphocytic leukemia. https://www.nccn.org/patients/guidelines/cll/index.html. Accessed April 10, 2019.
- American Cancer Society. Chronic lymphocytic leukemia. https://www.cancer.org/cancer/chronic-lymphocytic-leukemia.html. Accessed April 10, 2019.
- Kröber A, Seiler T, Benner A, et al. VH mutation status, CD38 expression level, genomic aberrations, and survival in chronic lymphocytic leukemia. Blood. 2002;100:1410-1416.
- Döhner H, Stilgenbauer S, Benner A, et al. Genomic aberrations and survival in chronic lymphocytic leukemia. N Engl J Med. 2000;343(26):1910-1916.
- Stilgenbauer S, Zenz T, Winkler D, et al. Genomic aberrations, VH mutation status and outcome after fludarabine and cyclophosphamide (FC) of FC plus rituximab (FCR) in the CLL8 trial. Presented at: 50th Annual ASH Meeting; December 6-9, 2008; San Francisco, CA. Abstract 781.
- Stilgenbauer S, Kröber A, Busch R, et al. 17p deletion predicts for inferior overall survival after fludarabine-based first line therapy in chronic lymphocytic leukemia: first analysis of genetics in the CLL4 trial of the GCLLSG. Blood (ASH Annual Meeting Abstracts). 2005;106(11):Abstract 715.
- Schnaiter A, Stilgenbauer S. 17p deletion in chronic lymphocytic leukemia: risk stratification and therapeutic approach. Hematol Oncol Clin North Am. 2013;27(2):289-301.
- Grever MR, Lucas DM, Dewald GW, et al. Comprehensive assessment of genetic and molecular features predicting outcome in patients with chronic lymphocytic leukemia: results from the US Intergroup phase III trial E2997. J Clin Oncol. 2007;25(7):799-804.
- Hallek M, Cheson BD, Catovsky D, et al. iwCLL guidelines for diagnosis, indications for treatment, response assessment, and supportive management of CLL. Blood. 2018;131(25):2745-2760.
- Döhner H, Stilgenbauer S, James MR, et al. 11q deletions identify a new subset of B-cell chronic lymphocytic leukemia characterized by extensive nodal involvement and inferior prognosis. Blood. 1997;89(7):2516-2522.