Rsph1, whose expression is testis-restricted [77] (see https://www.ncbi.nlm.nih.gov/gene/22092), directs the synthesis of a component of radial spokes head of cilia and sperm flagella [78], and mutations in this gene have been related to fertility problems in humans, resulting in primary ciliary dyskinesia and motility alterations of cilia and sperm [79]. This evidence concerns the gene RSPH1 and primary ciliary dyskinesia.