GSTM1 and cystic fibrosis: Materials and Methods: We retrospectively evaluated Hb levels in 35 subjects with CF (18 males, median age: 8 years; interquartile range (IQR): 6–13 years) treated with LI and 60 (24 males, median age: 10 years; IQR: 6–14 years) treated with ETI.