CLCN5 and cystinosis: However, in both diseases, the mutations are not in the trafficking machinery; Dent disease is caused by mutation in the endosomal chloride channel chloride channel protein 5 (ClC-5; also known as CLCN5) (Lloyd et al., 1996), and cystinosis by mutation of a lysosomal cystine transporter (Town et al., 1998).