TNF and juvenile idiopathic arthritis: In Hohlers’ study, subjects in JIA and control groups were all adults and the “juvenile onset” was defined as onset before age of 40 in their study.[41] In our study, we incorporated sufficient European samples assessing the association between TNF-α 238A/G or TNF-α 308A/G polymorphisms and JIA with the consideration of between-study heterogeneity.