Type І hyper IgM syndrome with novel mutation from India.

Hyper IgM syndrome is a primary immunodeficiency disorder characterized by normal or raised levels of immunoglobulin (Ig) M with low or absent IgG, IgA, and IgE. Five genetic causes of Hyper IgM have been identified. CD40L is deficient on T cells in Type І Hyper IgM, leading to defective interaction between T and B lymphocytes and consequently an inability to switch from production of IgM to other classes of antibodies. This manuscript reports a patient with X linked Hyper IgM (XHIGM) syndrome caused by a novel mutation in the CD40 Ligand (CD40L) gene and a favorable outcome after bone marrow transplantation.