The polymorphisms of the NAT2 gene have major pharmacogenetic considerations as they lead to adverse drug reactions and individual differences in drug response [51, 52]. NAT2 polymorphisms have also clinical importance, due to the fact that these polymorphisms lead to susceptibility to many diseases such as autoimmune diseases and cancer, for which the etiopathogenesis is affected by environmental factors [40, 47, 50, 56–64]. This evidence concerns the gene NAT2 and autoimmune disease.