Keywords: ERT; enzyme replacement therapy; CLN1; ceroid lipofuscinosis, neuronal-1; CLN2; ceroid lipofuscinosis, neuronal-2; LSD; lysosomal storage disorder; MU-6S-Palm-βGlc; 4-methylumbelliferyl-6-thiopalmitoyl-β-d-glucoside; NCL; neuronal ceroid lipofuscinosis;