Both interleukin-23A polymorphism and serum interlukin-23 expression are associated with Graves’ disease risk

•Two independent Chinese cohorts were used to study the genetic association between the IL-23A gene polymorphism (rs11171806) and GD susceptibility.•Higher IL-23 concentrations are found in GD patients of older age (⩾40) and female gender.•The individuals with A allele of rs11171806 are more vulnerable to Graves’ disease, which suggests that SNP of IL-23 gene may play an important role in GD development.•IL-23A gene is a genetic risk marker for GD in China.