Immunoglobulin G subclass deficiency is the major phenotype of primary immunodeficiency in a Korean adult cohort

Background/Purpose: Primary immunodeficiency disease (PID) is a rare disorder in adults. Serious forms are usually detected during infancy or childhood. Mild forms, however, may not be diagnosed until later in life, and some types of humoral immunodeficiency may occur in adulthood. The purpose of this study was to identify clinical features of PID in Korean adults. Methods: A retrospective study was performed on 55 adult patients who were diagnosed as having PID between January 1998 and January 2009 at Ajou University Hospital in Korea. Results: IgG subclass deficiency was the most common phenotype (76%, 37/55), followed by total IgG deficiency (20%, 11/55), IgM deficiency (17%, 4/55), common variable immunodeficiency (2%, 1/55), and X-linked agammaglobulinemia (2%, 1/55). IgG3 and IgG4 were the most affected subclasses. Upper and lower respiratory tract infections (76%) were the most frequently observed symptoms, followed by multiple site infection (11%), urinary tract infection, and colitis. Bronchial asthma and rhinitis were common associated diseases. Decreased IgG3 level was remarkable in patients with bronchial asthma. IgG subclass imbalance, increased IgG2 level with decreased IgG3 level, was found 30.7% of the patients with bronchial asthma. Conclusions: IgG and IgG subclass deficiency should be considered in adult patients presenting with recurrent upper and lower respiratory infections, particularly in those with respiratory allergies. IgG subclass imbalance would be associated with some part of bronchial asthma.