Thus, whereas the penetrance of the most common CFTR gene lesion, ΔPhe508 (rs113993960), in cystic fibrosis is very high, the penetrance of the CFTR Arg117His (rs78655421) mutation (in any allele combination) appears to be so low as to call into question its putative role as a pathological mutation (Thauvin-Robinet et al. 2009). The gene discussed is CFTR; the disease is cystic fibrosis.