There is no single cause of Hodgkin’s lymphoma. However, researchers have identified a number of factors that appear to make a person more likely to develop Hodgkin’s lymphoma. These risk factors include:

• Infectious mononucleosis (a viral infection typically caused by the Epstein-Barr virus). People who have had this infection are at a greater risk for Hodgkin’s lymphoma.
  
  A member of the herpes virus family, the Epstein-Barr virus is one of the most common human viruses. Researchers have found a link between the virus and Hodgkin’s lymphoma. The virus may cause suppression in the factor that prevents B-cells from growing too fast. Studies are investigating whether this suppression leads to the development of Reed-Sternberg cells and Hodgkin’s lymphoma.
  
  
• Lowered immunity. Patients with reduced immunity are at much greater risk for developing Hodgkin’s lymphoma and non-Hodgkin’s lymphomas. Lowered immunity may be found in people infected with the human immunodeficiency virus (HIV), those born with immune deficiencies, and those who have been treated with immunosuppressive drugs, such as those used with organ transplants. 

Other risk factors include:

• Age. Patients in young adulthood (age 15 to 40) or late adulthood (older than 55) are at an increased risk.
  
  
• Gender. Men are at a slightly increased risk, except for nodular sclerosis Hodgkin’s lymphoma (which occurs more often in women).
  
  
• Having a first degree relative with Hodgkin’s lymphoma. Patients with a parent, brother or sister with the disease are at an increased risk of developing it. However, family history is still uncommon and accounts for less than 10 percent of all the cases.

Hodgkin’s lymphoma does not appear to be related to specific gene mutations or environmental factors, as found with  many other cancers. Even though it may occur in several family members, researchers do not have reason to believe the disease is related to defective genes.