Therefore, the investigators initiated a multicenter case-finding study in Austria by screening patients with chronic kidney disease not yet on renal replacement therapy. Molecular isoforms of globotriaosylceramide (Gb3), characterized by different chain lengths of their N-acyl residues, will be determined in a urine sample. Characteristic parameters, including the ratio of C24/C18 isoforms will be used for identifying patients liable to have the disease. A positive result will be confirmed by biochemical and genetic testing.