When Fujita et al. studied HBV reactivation in 76,641 patients receiving treatment for rheumatoid arthritis from the Japanese National Database of Health Insurance Claims and Specific Health Checkups data between 2013 and 2016, HBsAg, anti-HBs and anti-HBc were examined in 21,633 (28.2%), 9593 (12.5%) and 11,213 (14.6%) patients, respectively, and nucleo(s)tide analogs were given in 59/76,641 (0.076%) subjects at baseline [6]. The gene discussed is KRT88P; the disease is rheumatoid arthritis.