DNAH1 and primary ciliary dyskinesia: To describe the subcellular localization of the IDA heavy chains DNAH1, DNAH6, and DNAH7 within the respiratory ciliary axoneme of PCD individuals carrying disease-causing variants in CCDC39 and CCDC40, we performed IF staining of 24 individuals, of whom 17 carry disease-causing variants in CCDC40 and seven in CCDC39.