It is an inherited disorder of the immune system that affects males. It is characterized by an abnormal immune response to infection by Epstein-Barr virus (EBV).
Mutation in the gene that helps in controlling the immune response to an EBV results in an abnormal response.
In addition to EBV infection patients are susceptible to B-cell lymphomas and recurrent infections. X-linked lymph proliferative syndrome occurs with a frequency of less than 1/million.