Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

X-Linked Lymphoproliferative Syndrome

(Duncan Syndrome)


James Fernandez

, MD, PhD, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University

Reviewed/Revised Jan 2023

X-linked lymphoproliferative syndrome is an immunodeficiency disorder that 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.

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 Infectious Mononucleosis Epstein-Barr virus causes a number of diseases, including infectious mononucleosis. The virus is spread through kissing. Symptoms vary, but the most common are extreme fatigue, fever, sore throat... read more Infectious Mononucleosis . The EBV causes several disorders, including infectious mononucleosis. Also, natural killer cells do not function.

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.

Symptoms of X-Linked Lymphoproliferative Syndrome

Diagnosis of X-Linked Lymphoproliferative Syndrome

  • Blood tests

  • Genetic testing

  • Sometimes bone marrow biopsy

Doctors suspect X-linked lymphoproliferative syndrome in young boys who have severe EBV infection, other characteristic problems, or family members with similar symptoms.

The diagnosis is confirmed by genetic testing. However, genetic testing can take weeks to complete, so doctors may do specialized blood tests, such as flow cytometry (analysis of proteins on the surface of white blood cells), to check for abnormalities in immune cells.

Laboratory and imaging tests are done yearly to check for lymphoma and anemia. Sometimes a bone marrow biopsy is done for these reasons.

Genetic testing is recommended for family members.

Treatment of X-Linked Lymphoproliferative Syndrome

  • Stem cell transplantation

About 80% of people who receive a stem cell transplant Stem Cell Transplantation Stem cell transplantation is the removal of stem cells (undifferentiated cells) from a healthy person and their injection into someone who has a serious blood disorder. (See also Overview of... read more survive. But without transplantation, three quarters of people die before age 10 years, and all die by age 40. Transplantation can cure X-linked lymphoproliferative syndrome if it is done before EBV infection or other disorders become too severe.

Rituximab (a drug that modifies the immune system's activity) can help prevent severe EBV infection before transplantation is done.

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

Drugs Mentioned In This Article

Generic Name Select Brand Names
RIABNI, Rituxan, RUXIENCE, truxima
quiz link

Test your knowledge

Take a Quiz!