Exosome secretion can be modulated by the activity of neutral sphingomyelinase 2 (nSMase2) and sphingomyelin synthase 2 (SMS2), suggesting unique roles for these enzymes in AD [178, 183], and additional significance for the disturbed ceramide levels observed in the course of the disease, as discussed above. The gene discussed is SGMS2; the disease is Alzheimer disease.