Successful discontinuation of immunoglobulin G replacement at age 10 in a patient with immunoglobulin G2 deficiency

CONTEXT: Immunoglobulin G2 deficiency that persists beyond the age of 6 years is likely to be permanent. CASE REPORT: We report on a young Japanese female, diagnosed as having immunoglobulin G2 deficiency and low anti-pneumococcal immunoglobulin G2 antibody levels when 3 years old, with a subsequent medical history of frequent respiratory infections and asthma. Monthly intravenous immunoglobulin replacement therapy was started at 4 years of age. After 8 years of age, an anti-pneumococcal immunoglobulin G2 trough level could be maintained with administration intervals longer than 6 weeks, and after 9 years and 10 months of age, therapy was discontinued. The frequency of hospital admissions was reduced by the introduction of the replacement therapy (from 8.4 times/year before the introduction to 1.1 times/year during the therapy). The patient was also able to discontinue daily medications for asthma, and serum immunoglobulin G2 was maintained at a normal level even after the cessation of replacement therapy. CONCLUSION: Termination of immunoglobulin replacement therapy in a patient with a symptomatic immunoglobulin G2 deficiency is possible, even for a child older than 6 years.