CST3 and Nager acrofacial dysostosis: In an observational study, Torralba-Cabeza et al. suggested that the Cystatin-C concentration is a superior and more sensitive marker than serum creatinine to detect early renal involvement or small decreases in the glomerular filtration rate in AFD patients of both genders, which can be important to evaluate the efficacy of the ERT and to be a good prognostic marker [28].