Similar to cystic fibrosis, where in vitro studies on Fisher rat thyroid cells expressing rare CFTR mutants were sufficient for the approval of ivacaftor for 23 rare CFTR mutations without need of patient data from clinical trials.48, 50 Our functional assay using TopF‐PC reliably reproduced lipid transport and ATPase activity studies of the mutant proteins performed by Matsumura et al25, 26 (Table S1) and also replicated dose‐response relations of genistein in CFTR,39, 42, 43 making it suitable for high‐throughput screens to identify other substances that act as potentiators for ABCA3. The gene discussed is ABCA3; the disease is cystic fibrosis.