GSTM1 and juvenile idiopathic arthritis: Molecular techniques now capable of distinguishing all three GST genotypes (homozygous presence: 1/1, heterozygous: 1/0 or 0/1, and homozygous deletion: 0/0) in comprehensive multicentric cohort studies on different populations might yield contrasting findings related to the association between GSTT1, GSTM1, and other GTS genetic variants and the effectiveness of MTX in patients with JIA.