TGFB1 and cystic fibrosis: The association of TGFβ1 codon 10 CC genotype and the TT genotype of −509 with more severe lung disease in delta F 508 homozygous cystic fibrosis patients was shown by Drumm and coworkers [3] in a large trial involving 808 CFTR F508 del homozygous patients.