Neonatal Fc receptor (FcRn) plays an important role in regulating IgG homeostasis in the body. Changes in FcRn expression levels or activity caused by genetic polymorphisms of FCGRT, which encodes FcRn, may lead to interindividual differences in pharmacokinetics of therapeutic antibodies. In this study, we sequenced the 5'-flanking region, all exons and their flanking regions of FCGRT from 126 Japanese subjects. Thirty-three genetic variations, including 17 novel ones, were found. Of these, two ...