TTC21B and Jeune syndrome: To date, mutations in 10 genes have been shown to cause Jeune syndrome, eight leading to classic JATD with ciliogenesis defects due to IFT dysfunction; these encode heavy and intermediate IFT dynein subunits DYNC2H1, WDR34 and WDR60 (refs 12, 13, 14, 15, 16), IFT complex B components IFT80 and IFT172 (refs 18, 20), and IFT complex A components WDR19/IFT144, TTC21B/IFT139 and IFT140 (refs 21, 22, 23).