Liver disease predicts mortality in patients with X-linked immunodeficiency with hyper-IgM but can be prevented by early hematopoietic stem cell transplantation

X-linked immunodeficiency with hyper-IgM (XHIM) is a severe primary immunodeficiency disorder characterized by low levels of, or absence of IgG, IgA, and IgE, with normal to raised serum IgM concentrations.1 XHIM results from mutations in the CD40 ligand (CD40L) gene found on activated CD4 T cells2; disruption of this gene results in aberrant interaction with CD40 on B-cell membranes, thus inhibiting B-cell proliferation and immunoglobulin class switching.3