Dynein-attachment factor required for cilia motility. Homodimer. Expressed in all cells bearing motile cilia. Expression is regulated by foxj1. Defects in ccdc103 are the cause of the schmalhans phenotype and show a curved body axis, randomized left-right asymmetry and pronephric kidney cysts, which are characteristic features of ciliopathies. Cilia completely lack both inner dynein arms (IDAs) and outer dynein arms (ODAs) while cilia length in these mutants is not altered. Belongs to the CCDC103/PR46b family.