X-linked lymphoproliferative syndrome

[Julene]

X-linked lymphoproliferative syndrome results from an abnormality in T cells and natural killer cells and results in an abnormal response to Epstein-Barr virus infection.

People with X-linked lymphoproliferative syndrome develop a serious, sometimes fatal form of infectious mononucleosis after being infected with Epstein-Barr virus.
Doctors diagnose the disorder by genetic testing and sometimes other tests.
Stem cell transplantation is necessary for survival and may cure the disorder.

(See also Overview of Immunodeficiency Disorders.)
X-linked lymphoproliferative syndrome is a primary immunodeficiency disorder. It is inherited as an X-linked recessive disorder. X-linked means that the disorder is due to a mutation in one or more genes on the X (sex) chromosome. X-linked recessive disorders occur only in boys.
There are two types, which result from different gene mutations but cause similar symptoms.
In the first type, too many white blood cells (which help the body fight infection) are produced in response to Epstein-Barr virus (EBV) infection. The EBV causes several disorders, including infectious mononucleosis. Also, natural killer cells do not function. Natural killer cells are a type of white blood cell that recognizes and kills abnormal cells (such as certain infected cells and cancer cells).
The second type can cause a rare but serious disorder called hemophagocytic lymphohistiocytosis, which causes immunodeficiency in infants and young children. In hemophagocytic lymphohistiocytosis, too many blood cells in the immune system are activated. The result is widespread inflammation. Sometimes this overactivation is triggered by infectious organisms such as EBV.