CTNS and cystinosis: Although cystinosis is a monogenic disease, it has three major clinical presentations depending on the severity of mutations affecting the CTNS gene: the infantile nephropathic form (MIM: 219800, ORPHA411629), the juvenile nephropathic form (MIM: 219900, ORPHA411634) and the ocular non-nephropathic form (MIM: 219750, ORPHA411641) [8].