Signs and symptoms of XLP1

The symptoms of XLP1 are very variable and can be divided into three groups as follows:
Haemophagocytic lymphohistiocytosis (HLH)

HLH occurs when the body reacts inappropriately to a ‘trigger’, usually an infection. Instead of fighting off the infection, some white blood cells (T-cells and macrophages) become over-activated, causing severe inflammation and damage to tissues, such as the liver, spleen and bone marrow. HLH affects around half of all children diagnosed with XLP1. Immunodeficiency UK has a separate information devoted to HLH, available here.


This is the medical term for reduced levels of antibodies (immunoglobulin) in the blood, which leads to recurrent infections, such as coughs, colds and upset stomach.


Children with XLP1 have a greatly increased risk of developing lymphoma (cancer of the immune system cells) compared with the general population. Lymphoma causes symptoms such as fever, fatigue, weight loss, loss of appetite and/or sudden enlargement of one or a few lymph nodes.

Other symptoms

A variety of other symptoms have been reported. These include bone marrow
failure, causing anaemia and vasculitis.

Children often have an unremarkable childhood until primary-school age and
exposure to the Epstein-Barr virus. This appears to trigger the development of
symptoms, although the number and severity of symptoms is variable.