XLP affects male children and is characterized by a life-long vulnerability to Epstein-Barr virus (EBV), a type of herpesvirus that affects approximately 95 percent of U.S. adults and usually does not cause any symptoms other than a brief infection or mononucleosis. Boys with XLP, however, can have severe reactions to EBV infections.
XLP is associated with mutations in a gene called SH2DIA located on the X chromosome. These mutations cause defects in T- and B-cell interactions, which generate abnormal immune responses to EBV.
Boys with XLP are healthy until they are exposed to EBV. Then, they can become seriously ill and experience swollen lymph nodes, enlarged liver and spleen, hepatitis, and lymphoma.
XLP can be diagnosed based on a hyperactive response to viral infection such as severe mononucleosis or by a blood test showing low antibodies in the blood.
Immunoglobulin (antibody) replacement therapy can be used to treat XLP but will not protect a child against EBV infection. Bone marrow or umbilical cord blood transplantation can effectively treat XLP.
Last Updated July 17, 2012
Last Reviewed October 15, 2010