hyper-igm syndromes are characterized by profound reduction of serum igg, iga, and ige levels with normal or increased concentrations of serum igm. cd40 ligand deficiency is x-linked form of the disease, which results in a lack of immunoglobulin class switching from igm to igg in b cells. in addition to the recurrent infections, a number of patients suffer from neutropenia. there are some evide...