We showed that the endolysosomal dysfunction in ANCL patient-derived cells is a direct consequence of CSPα in the endolysosome, affecting the levels of lysosomal proteins (LAMP1, LAMP2, and V-ATPase B1/2), Rab7 and synaptosome-associated protein of 23 kDa (SNAP23)89. The gene discussed is LAMP1; the disease is adult neuronal ceroid lipofuscinosis.