ALK Mutation (Gene Rearrangement)
- Also Known As:
- EML4-ALK Fusion Protein
- ALK Gene Rearrangement
- ALK Gene Fusion
- Formal Name:
- ALK (Anaplastic Lymphoma Receptor Tyrosine Kinase) Gene Rearrangement

This page was fact checked by our expert Medical Review Board for accuracy and objectivity. Read more about our editorial policy and review process.
At a Glance
Why Get Tested?
To detect an ALK gene rearrangement in tumor tissue in order to guide non-small cell lung cancer therapy
When To Get Tested?
When you have been diagnosed with non-small cell lung cancer and your health care practitioner is considering a therapeutic management plan that may include an ALK kinase inhibitor such as crizotinib
Sample Required?
A tumor tissue sample is obtained through a biopsy procedure or sometimes collected during surgery. The tumor tissue is typically evaluated by a pathologist prior to testing.
Test Preparation Needed?
Usually no preparation is needed.
What is being tested?
ALK is a short name for the anaplastic lymphoma receptor tyrosine kinase gene. This test detects specific rearrangements in the ALK gene in cancer cells and tissue. The presence of these changes makes it more likely that a person with non-small cell lung cancer will respond to a targeted drug therapy.
The ALK gene codes for a protein called anaplastic lymphoma kinase. It is part of a family of proteins called receptor tyrosine kinases that regulate cell growth.
About 4-5% of people who have non-small cell lung cancer, the most common type of lung cancer, have an alteration on chromosome 2 that leads to the fusion of the ALK gene with another gene (fusion partner). The most common ALK fusion partner is a gene called EML4 and results in the production of an EML4-ALK fusion protein. It is a rare mutation most commonly seen in people who have never smoked or are light smokers, especially women of Asian descent.
There are several different methods of testing for ALK mutations, but all of them involve evaluating either the ALK gene rearrangement or the altered ALK protein in tumor tissue.
Common Questions
View Sources
Sources Used in Current Review
2018 review performed by Mutasim Elfahal, PhD, DABCC.
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Lindeman NI, et al. Updated Molecular Testing Guideline for the Selection of Lung Cancer Patients for Treatment With Targeted Tyrosine Kinase Inhibitors: Guideline From the College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology. J Mol Diagn. 2018 Mar;20(2):129-159.
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Chia PL, Mitchell P, Dobrovic A, John T. Prevalence and natural history of ALK positive non-small-cell lung cancer and the clinical impact of targeted therapy with ALK inhibitors. Clin Epidemiol. 2014 Nov 20;6:423-32.
Sources Used in Previous Reviews
Markman, M. (Updated 2013 July 15). Genetics of Non-Small Cell Lung Cancer. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/1689988-overview. Accessed July 2013.
Lindeman, N. et. al. (2013 June). Molecular Testing Guideline for Selection of Lung Cancer Patients for EGFR and ALK Tyrosine Kinase Inhibitors, Guideline from the College of American Pathologists, International Association for the Study of Lung Cancer, and Association for Molecular Pathology. Arch Pathol Lab Med v 137, [On-line information]. Available online at http://www.archivesofpathology.org/doi/pdf/10.5858/arpa.2012-0720-OA. Accessed July 2013.
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Yi E., et al. Correlation of IHC and FISH for ALK Gene Rearrangement in Non-small Cell Lung Carcinoma: IHC Score Algorithm for FISH. Journal of Thoracic Oncology March 2011 – Volume 6 – Issue 3 – Pp 459-465. Available online at http://journals.lww.com/jto/Fulltext/2011/03000/Correlation_of_IHC_and_FISH_for_ALK_Gene.8.aspx#. Accessed November 2013.
Gregory J. Tsongalis, PhD, HCLD, CC, Professor of Pathology, Director, Molecular Pathology, Dartmouth Hitchcock Medical Center and Geisel School of Medicine at Dartmouth, Lebanon, NH.
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