CD8A and mucopolysaccharidosis type 1: However, it is important to investigate whether in that setup, no pre-existing CD8 positive effector T cells (CTLs) would be present which could hamper the efficiency of lentiviral gene therapy, as has been previously shown for mucopolysaccharidosis I.76Future experiments should therefore focus on the conditions required to combine ERT with gene therapy when ERT is provided prior to gene therapy.