#$%^&*AU2013206657A120130718.pdf#####ABSTRACT Provided herein are methods and compositions for treating a subject suffering from a deficiency in a-L-Iduronidase in the CNS. The methods include systemic administration of a bifunctional fusion antibody comprising an antibody to a human insulin receptor and an a-L-Iduronidase. A therapeutically effective systemic dose is based on the specific CNS uptake characteristics of human insulin receptor antibody-a-L-Iduronidase fusion antibodies as described herein. -484478550_1 (GHMatters) P83171.AU.1