XLP2 is an X-linked primary immune deficiency with symptom onset usually in the first years of life, although later onset may occur. Features are compatible with immune dysregulation and include hemophagocytic lymphohistiocytosis (HLH), often associated with chronic Epstein-Barr virus (EBV) infection, splenomegaly, fever, colitis or inflammatory bowel disease (IBD), and recurrent infections. Laboratory abnormalities are variable, but can include hypogammaglobulinemia, cytopenias, and low levels of a particular subset of T cells known as NKT (or iNKT) cells. [From OMIM]