These results suggest that NEU1 deficiency due to NEU1 G227R and V275A/R347Q mutations may result in impaired lysosomal exocytosis in sialidosis-iNPCs and also demonstrate that the features of neuronal and biochemical defects associated with NEU1G227R and NEU1V275A/R347Q mutations can be effectively recapitulated in our sialidosis-iNPC models. The gene discussed is NEU1; the disease is sialidosis.