Bi-allelic PCD pathogenic variants in autosomal recessive pattern inheritance were found in the following order: CCDC40 [8/49 (16%) patients], DNAH5 [4/49 (8%) patients], RSPH1 and DYX1C1 [3/49 (6%) patients], DNAAF3 [2/49 (4.1%)], and 1/49 (2%) for the following genes: CCDC39, DNAI2, DNAH11, RPGR and CCDC151. An overview and considerations regarding the genetic screening in the use of pathogenic variants are shown in brief in Table 3, and the complete overview is shown in the Supplementary File (Table S2). The gene discussed is DNAAF4; the disease is primary ciliary dyskinesia.