Familial IgG3 subclass deficiency: A report of two cases

Abstract

Primary immunodeficiency in adults is thought to be underestimated in Korea. IgG subclass deficiency, defined as a deficiency at least among the 4 subtypes of IgG subclass, IgG1, IgG2, IgG3, and IgG4, results in recurrent infections, in which IgG3 subclass deficiency (IgGSD) is the most commonly found in adult asthmatic patients. Herein, we report 2 cases of familial IgG3SD. In family 1, a female patient aged 17 years with allergic rhinitis (AR) had recurrent upper respiratory infections (URIs), and gastroenteritis. Her mother aged 50 with AR had recurrent URI, otitis media, urinary tract infection, gastroenteritis, and oral ulcer. A younger sister aged 9 years with AR and asthma had recurrent URI almost all the year round. The serum IgA level was found to be lower than the normal level in her mother and the patient, and IgG3 was decreased in the patient and her sister. The IgG3 level of mother showed within the lower normal limit. In family 2, the mother aged 39 years with nonallergic rhinitis had recurrent URI and oral ulcer. Her son aged 16 years and daughter aged 13 years with AR and asthma had recurrent URI, resulting in uncontrolled asthma. Family 2 was found to be IgG3 deficiency in mother and son, and IgA deficiency in son. The IgG3 level of daughter was within the lower normal level. Mother and the first daughter in family 1 as well as mother and son in family 2 was treated with intravenous immunoglobulin, and their recurrent URI reduced. We reported 2 cases of familial IgG3SD.