Primary isolated IgM deficiency accounted for 0.1% of hospital admissions; secondary IgM deficiency for 2.0%. Although 19% were asymptomatic the rest of 89 subjects (4M:1F) suffered infection (60%), septicemia (36%), atopy (22%), splenomegaly (11%), neoplasia(7%) and autoimmune disorders (3%) with a mortality of 10%. Serious early treatment is needed to avert death from unopposed spread of organisms throughout the blood. Qualitative IgM deficiency (absence of isohemagglutinins) and delayed maturation of IgM can result in similar symptomatology.
原发性孤立性IgM缺乏症占住院患者的0.1%；继发性IgM缺乏症占2.0%。虽然19%的患者无症状，但其余89名受试者（4名男性：1名女性）出现感染（60%）、败血症（36%）、特应性疾病（22%）、脾肿大（11%）、肿瘤（7%）和自身免疫性疾病（3%），死亡率为10%。需要尽早进行积极治疗，以避免因病原体在血液中无阻碍地扩散而导致死亡。定性IgM缺乏症（缺乏同种血凝素）和IgM成熟延迟可导致相似的症状。
