Recent study demonstrated that M55V variant in SUMO4 at IDDM5 was associated with susceptibility to type 1 diabetes. Subsequent studies, however, showed inconsistency in the association. To clarify the population-wide effect on the association of SUMO4 with type 1 diabetes, we have performed meta-analysis including our own data in Asian populations, which confirmed a highly significant association in Asian populations (summary odds ratio [OR]: 1.29, P = 7.0 x 10(-6)), but indicated significant heterogeneity in the genetic effect of the SUMO4 gene on type 1 diabetes among diverse ethnic groups. These observations indicated the association of SUMO4 with type 1 diabetes in Asian populations.