Here we report that an SNP (rs3748079) located in a promoter region of the inositol 1,4,5-triphosphate receptor type 3 (ITPR3) gene on chromosome 6p21 was significantly associated with SLE in two independent Japanese case-control samples [P=0.0000000178 with odds ratio of 1.88, 95% confidence interval (CI) of 1.51-2.35].