If prevalence of Japanese PCD is estimated at 1:20,000 ( = 0.005%) (Takeuchi et al., 2018), PCD caused by this deletion in DRC1 accounts for 8% ( = 0.0004/0.005), indicating that this DRC1 mutation may be the most common cause of PCD in Japan, since, so far, no mutation hotspots of known PCD genes have been identified in Japan (Takeuchi et al., 2018). Here, DRC1 is linked to primary ciliary dyskinesia.