Disclosed are methods and compositions for determining immunodominant peptides of target enzymes used in enzyme replacement therapy for lysosomal storage disorders. More specifically disclosed are immunodominant peptides for N-acetylgalactosamine-6-sulfatase (GALNS). Also disclosed are methods of inducing oral tolerance towards a target enzyme through oral administration of immunodominant peptides prior to commencing enzyme replacement therapy. More specifically disclosed is a method of inducing oral tolerance for GALNS, by orally administering specific immunodominant peptides for GALNS; in subjects suffering from mucopolysaccharidosis type IVA prior to commencing enzyme replacement therapy using GALNS.