Feline Mucopolysaccharidosis type VII (MPS VII)
Feline mucopolysaccharidosis type VII (MPS VII), also known as Sly syndrome in humans, is a rare lysosomal storage disorder, causing typically progressive skeletal and ocular abnormalities, caused by more than 50 different mutations in the β-glucuronidase gene (GUSB). In addition to the well-known human disorder, MPS VII also has been identified in several animal species including mice and dogs. Mucopolysaccharidosis VII also was reported in 4 domestic shorthair (DSH) cats. However, only two cats have been studied at the molecular genetic level.
Characteristics and Symptoms
Feline mucopolysaccharidosis type VII (MPS VII) is characterized by early age of onset, dwarfism, facial dysmorphia, bone and joint abnormalities, organomegaly and neurological signs with variable degree of severity.
Currently, MPS VII and other MPS disorders lack an efficient clinical treatment despite intense experimental investigations offering promising results with novel gene transfers, such as bone marrow transplantation, enzyme replacement treatment and gene treatment. These treatments have demonstrated a great capacity to prevent many of the clinical features but once clinical signs occur, MPS VII is not reversible. Symptomatic treatment, pain alleviation, and physiotherapy can be offered before euthanasia is elected.
Feline mucopolysaccharidosis type VII (MPS VII) is caused by mutations in GUBS (β-glucuronidase) gene. It is inherited in a autosomal recessive manner. When mating two carriers (heterozygotes) at conception each kitten has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
A DNA test for known mutations in GUSB gene causing mucopolysaccharidosis type VII (MPS VII) is available for all cat breeds. However, general screening is not recommended.
Fyfe, J.C., Kurzhals, R.L., Lassaline, M.E., Henthorn, P.S., Alur, P.R., Wang, P., Wolfe, J.H., Giger, U., Haskins, M.E., Patterson, D.F., et al. (1999). Molecular basis of feline beta-glucuronidase deficiency: an animal model of mucopolysaccharidosis VII. Genomics 58, 121–128.
Wang, P., Sorenson, J., Strickland, S., Mingus, C., Haskins, M.E., and Giger, U. (2015). Mucopolysaccharidosis VII in a Cat Caused by 2 Adjacent Missense Mutations in the GUSB Gene. J. Vet. Intern. Med. 29, 1022–1028.