The cause or causes of lymphoma are largely a mystery. There may be some genetic predisposition, or it may be caused by an environmental trigger such as pollution. There is not, however, sufficient evidence to provide a definitive answer. It has been shown that some NHLs of the digestive tract such as mucosa-associated lymphatic tissue (MALT) lymphomas may be caused by Helicobacter pylori infection. There also seems to be a link with Epstein-Barr virus and gene relocation in some forms of Burkitt’s lymphoma.