X-linked lymphoproliferative (XLP) syndrome is a rare recessive genetic disorder that can be divided into two types based on its genetic cause and pattern of signs and symptoms. X-linked lymphoproliferative syndrome type 1 (XLP1), also known as classic XLP, is caused by mutations in SH2D1A; XLP type 2 (XLP2) is caused by the XIAP gene.
XLP1 is characterized by a severe Epstein-Barr virus (EBV)–induced hemophagocytic lymphohistiocytosis (HLH) or severe mononucleosis, malignant lymphoma, dysgammaglobulinemia, and common variable immunodeficiency (CVID).
Neither malignant lymphoma nor CVID have been reported in XLP2. Patients with XLP2 are more likely to develop HLH without EBV infection, splenomegaly, and may also have inflammation of the large intestine (colitis).
Currently, the only definitive treatment available for XLP1 patients is allogeneic hematopoietic stem cell transplant (HSCT).
However, depending on clinical features, less aggressive treatments may be adopted, particularly if a suitable donor for transplant is not available. As symptoms may not all be present simultaneously, and they may be of varying severity, treatment options that target specific clinical phenotypes may be appropriate.
For patient education information, see the Infections Center, as well as Mononucleosis.