mucopo

Mucopolysaccharidosis

What is Mucopolysaccharidosis type IIIB (MPS IIIB).
The disease MPS IIIB, also known as Sanfilippo syndrome type IIIB, is an inherited disease classified as a lysosomal storage disease (LSD). Lysosomes are "bags" within cells of the body, filled with special enzymes which disassemble molecules in an orderly manner. If one of the enzymes is missing, due to mutations in the gene for that enzyme, the disassembly stops, and undegraded molecules accumulate in lysosomes (hence the term LSD), and the cells become sick or die, which leads to disease. The compound accumulating in MPS IIIB is heparan sulfate and the affected enzyme is N-acetyl-a-D-glucoseaminidase (NAGLU).

What are the symptoms of MPS IIIB.
The clinical signs in the dogs are related to brain disease, appear between 2-4 years of age, and include tremor, and difficulty in balancing, walking, and negotiating obstacles such as stairs. The disease is progressive and unfortunately there is no treatment for this disease, most owners chose euthanasia, usually 1-2 years after recognizing clinical signs. Once an animal has begun to show clinical signs, all that can be done is to provide a safe environment, such as one without stairs, or obstacles, which might lead to falls or make getting around difficult. The decision of when to elect euthanasia for a sick pet is a difficult one, and must be made by balancing the importance of the bond between the owner and their pet, and the quality of life of their pet. Under no circumstances can we recommend that non-symptomatic animals be euthanized. Although the lifespan of dogs with this disease is much shorter than normal, until they become clinically affected, they are absolutely normal, and depending on the clinical course of the disease in the individual, they can have many months of quality life after clinical signs appear. The difference between owning an affected versus and unaffected dog, is that the owner has a very good idea of when and why they may face the decision to elect euthanasia for their pet.

How is MPS IIIB inherited?
The inheritance pattern of MPS IIIB is autosomal recessive. Both males and females are equally capable of having the disease, or of being carriers. Carriers are absolutely normal, and will not have signs of the disease.