GSTM3 and COVID-19: GSTM1 and GSTT1 gene deletions as well as GSTP1 rs1138272 and rs1695, GSTA1 rs3957357, and GSTM3 rs1332018 polymorphisms have been investigated in a cohort of 207 COVID-19 patients and 252 healthy individuals of Serbian, Caucasian origin.