In a phase 2 study involving adult CF patients (NCT00237380), no change in the mean proportion of CFTR mRNA isolated from the nasal epithelium of treated patients relative to wild-type CFTR mRNA was observed during the treatment with 4, 4, 8 and 10, 10, 20 mg/kg PTC124 (as measured by real-time PCR). The gene discussed is CFTR; the disease is cystic fibrosis.