However, AD neurons show a large endosomal accumulation of APP products (Aβ and C99) and in particular the accumulation of C99 has been found to occur at very early stages even before the appearance of any detectable Aβ plaques [86], suggesting that C99 (possibly in association with ILVs) might be involved in the onset of AD. The gene discussed is APP; the disease is Alzheimer disease.