GST activity was significantly increased in the pediatric CF patients infected with P. aeruginosa as well as S. aureus versus control subjects (2.51 ± 0.88 and 2.57 ± 0.79 U/g Hb versus 0.77 ± 0.16 U/g Hb; P < 0.05). The gene discussed is GSTM1; the disease is cystic fibrosis.