Thirty-eight pwCF carrying rare (non-F508del) CFTR variants were selected for this study, among those available at the Cystic Fibrosis Reference Center of Lazio Region, AOU Policlinico Umberto I (Rome, Italy), and at the Cystic Fibrosis Center at AOUI of Verona, to test their in vitro responses to modulators. The gene discussed is CFTR; the disease is cystic fibrosis.