Common Symptoms
Mucopolysaccharidosis (MPS) VI (Miniature Schnauzer Type) is an inherited Lysosomal Storage Disorder. Affected dogs have insufficient activity of the Enzyme beta-glucuronidase, which is responsible for breaking down glycosaminoglycans (GAGs). GAGs are an important component of Connective Tissue. In affected dogs, there is an accumulation of breakdown products in cells causing abnormal growth and function of various organ systems. Clinical signs of MPS VI are most commonly associated with accumulations in the bones and joints. Affected dogs have variable clinical signs, but MPS is suspected when dogs show developmental abnormalities such as stunted growth, enlarged head with a pronounced underbite, and abnormal spinal alignment. A veterinarian may assess internal organ abnormalities using an ultrasound. While affected dogs can survive with assistance for several years, they are often euthanized due to a poor quality of life.
Testing Tips
Genetic testing of the ARSB gene will reliably determine whether a dog is a genetic Carrier of mucopolysaccharidosis VI (Miniature Schnauzer Type). This disease is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the ARSB gene mutation. Reliable genetic testing is important for determining breeding practices. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Dogs that are not carriers of the mutation have no increased risk of having affected pups.
There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.
References
-
Pérez ML, Kridel HA, Gallagher A, Sheppard BJ, Reese S, Kondo H, Alleman R, Giger U. Mucopolysaccharidosis type VI in a juvenile miniature schnauzer dog with concurrent hypertriglyceridemia, necrotizing pancreatitis, and diabetic ketoacidosis. Can Vet J. 2015 Mar;56(3):272-7.
[PubMed: 25750448]
-
Raj K, Berman-Booty L, Foureman P, Giger U. ARSB gene variants causing Mucopolysaccharidosis VI in Miniature Pinscher and Miniature Schnauzer dogs. Anim Genet. 2020 Dec;51(6):982-986.
[PubMed: 32985704]
