Therefore, we concluded that lyso-SM-509 is a PPCS.121) From the simultaneous analysis of PPCS and SPC in the serum/plasma of healthy subjects, patients with NPC and other lysosomal diseases, and patients suspected of NPC without NPC1 or NPC2 mutations, PPCS in patients with NPC was significantly higher than that in the other subjects. The gene discussed is NPC1; the disease is nasopharyngeal carcinoma.