Hyper-IgM syndrome is a condition characterized by normal or increased serum IgM concentrations associated with low or absent serum IgG, IgA, and IgE concentrations, indicating a defect in the class-switch recombination (CSR) process.
For a discussion of genetic heterogeneity of immunodeficiency with hyper-IgM, see HIGM1 (308230). [from
OMIM]