Hyper immunoglobulin M syndrome in a 15-year-old boy caused by a Gly219Arg missense mutation

摘要

Hyperimmunoglobulin M syndrome is a primary immunodeficiency disorder characterized by low or absent immunoglobulin (Ig) G, IgA, and IgE, with normal or elevated IgM levels.1 X-linked hyper-IgM syndrome (X-HIGM or HIGM1) is the most frequent subtype of HIGM, which is caused by mutations in CD40 ligand (CD40L or CD154) gene encoding for the CD40L expressed on activated T cells.1 CD40L plays an important role in class switching and maturation of B-lymphocytes by interacting with its receptor CD40 on B-cells. CD40L is also important for activation of T-cells. Mutations of CD40L result in a combined T- and B-cell immunodeficiency. Thus, patients with X-HIGM are susceptible to bacterial, fungal, and opportunistic microorganisms.1"3 We report a case of X-HIGM caused by a c.655G>A missense mutation, resulting in decreased but not absent CD40L expression and function on activated T-cells.