An association study in a Japanese population showed that the (T)7-IL-21 allele within the IL-21 gene was significantly more frequent in patients with type 1 diabetes than in control subjects (20.4 vs. 13.6%; P=0.03), indicating that the allele may be positively associated with type 1 diabetes and possible involved in the IL-21 pathway in the pathogenesis of the disease (30). This evidence concerns the gene IL21 and type 1 diabetes mellitus.