Abstract

Among the primary antibody deficiency syndromes, severe selective IgM deficiency (also previously known as type V dysgammaglobulinaemia) is rare, and the majority of previous reports have indicated a fatal outcome. Three adult patients who were found to have a persistently low serum IgM are described. This deficiency was not obviously related to their presenting illness; in two of the patients, who were investigated in detail, it appeared to be of no immediate consequence.