In the second group of ciliopathy models, which include Bardet–Biedl syndrome (Bbs4-/-, Mkks-/- (Bbs6-/-), and Bbs8-/-), Alström syndrome (Alms1-/-), and Meckel–Gruber syndrome (Tmem67-/-), the primary cilia are present with relatively normal SHH signaling and normal cochlear lengths (Table 2; Abdelhamed et al., 2015; Ezan et al., 2013; Jagger et al., 2011; Leightner et al., 2013; May-Simera et al., 2015; Rachel et al., 2012; Ross et al., 2005). This evidence concerns the gene BBS4 and Bardet-Biedl syndrome.