Scientists at the Institute of Cancer Research (ICR) in London have discovered a genetic link between Hodgkin's lymphoma and multiple sclerosis (MS), suggesting that there may be a shared mechanism of action the triggers the two diseases.
Analyzing the genes of more than 12,000 people, the researchers found two new gene variants that increase the risk of developing Hodgkin's lymphoma significantly.
According to the study, “One of these variants is linked to a gene known as EOMES that helps develop cell-mediated immunity, and is also a known risk factor for MS. This might explain why cases of Hodgkin's lymphoma and MS are found to cluster together in families.”
What Is Hodgkin's Lymphoma?
Hodgkin's lymphoma is a cancer that starts in the white blood cells, or lymphocytes, found in the lymphatic system, which is part of the body’s immune system. Lymph nodes, lymph fluid, and lymph vessels, which transport the fluid throughout the body, all make up the lymphatic system.
Because this system runs throughout the body, Hodgkin's lymphoma can start nearly anywhere. According to the American Cancer Society (ACS), the major sites are the lymph nodes, spleen, thymus, bone marrow, and digestive tract.
Lymphocytes are also thought to play an important role in MS. Normally, lymphocytes defend the body against foreign invaders like viruses and bacteria. In MS, the lymphocytes are misdirected and attack the protective covering of the nerves in the brain and spinal cord.
In a study conducted in Denmark and published in 2004, researchers followed 11,790 patients with multiple sclerosis and 19,599 of their first-degree relatives and monitored them for the development of Hodgkin's lymphoma.
They concluded that “the observed familial clustering of multiple sclerosis and young-adult-onset Hodgkin's lymphoma is consistent with the hypothesis that the two conditions share environmental and/or constitutional etiologies.” The discovery of a genetic connection between Hodgkin's lymphoma and MS is exciting progress toward understanding both, suggesting the possibility of a mutual trigger.
EBV: A Possible Culprit?
If finding an MS trigger were a “whodunit,” the Epstein Barr virus (EBV), responsible for mononucleosis, would look like a handsome suspect. It is one of the known risk factors for developing Hodgkin's lymphoma and is commonly found in people with MS. EBV and MS appear to relapse together in those who have both.
“Epstein Barr virus is the virus that causes glandular fever (mononucleosis),” explains Cancer Research U.K. on their website. “People who have had glandular fever have an increased risk of Hodgkin's lymphoma afterwards. A study published in December 2011 estimated that almost half of the cases of Hodgkin's lymphoma in the U.K. are related to EBV infection.”
Not all people with Hodgkin's lymphoma or MS have been exposed to EBV, however, suggesting that if the virus is a trigger for either, it’s certainly not the only factor.
Researchers are working on the first human trials for a vaccine to fight EBV. Further research is needed to explore the connection between Hodgkin's lymphoma and MS.
The fact that both involve the immune system, share a genetic risk factor, and seem to cluster in families suggests that we are getting closer to solving the mysteries surrounding both diseases and are perhaps one step closer to a cure.