Mice homozygous for the "mps" (mucopolysaccharidosis type VII or MPS VII) mutation are devoid of expression of the lysosomal enzyme beta glucuronidase. Homozygous animals are viable, but females have a deficiency in lactation. Skeletal and connective tissue anomalies in both males and females are believed to prevent successful breeding. As this mutation is recessive, heterozygous mice are phenotypically similar to wildtype. Homozygotes exhibit short and thickened long bones (smaller than heterozygous or wildtype littermates), "pug type" appearance of the nose, hepatomegaly, splenomegaly, corneal clouding, and deafness. In appearance, homozygous KitW-41J mice are mostly white with black eyes and brown or grey spots. They are fertile, distinct from mice with other alleles of Kit, and have the impaired hemopoiesis causing mild, normochromic, macrocytic anemia. MPS VII mice are a model of the beta glucuronidase enzyme deficiency in humans called Sly Disease. They may be useful in developing new therapies (enzyme replacement, cell transplantation, gene therapy) broadly applicable to other lysosomal storage diseases. This strain, with combined KitW-41J and Gusbmps, provides a genetically myeloablated population in which to study stem cell engraftment and reconstitution.
