NCIt definition : 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.;