A rare dysgammaglobulinemia characterized by low or undetectable serum levels of immunoglobulin class m (igm). it is an uncommon primary antibody deficiency. it is most likely an inherited immunodeficiency. it may be caused by decreased or inefficient production of igm from progenitor b cells without any corresponding decreases in the other isotypes. there is a widely variable clinical course. some affected individuals may be asymptomatic while others show increased susceptibility to infection, malignancy and autoimmune disorders.