i

We demonstrated previously that short term administration of recombinant b-glucuronidase to newborn mice with mu-copolysaccharidosis type VII reduced lysosomal storage in many tissues. Lysosomal storage accumulated gradually af-ter cessation of enzyme replacement therapy. Mice alive at 1 yr of age had decreased bone deformities and less lysosomal storage in cortical neurons. Here we compare the effects of long term enzyme replacement initiated either at birth or at 6 wk of age, and of enzyme administration initiated at birth followed by syngeneic bone marrow transplantation (BMT) at 5 wk of age. Several mice from each treatment group lived to at least 1 yr of age. Liver and spleen samples had b-glucuronidase levels ranging from 2.4 to 19.8 % of norma