Lysosomal storage disease due to arylsulfatase B (ARSB) deficiency, with tissue accumulation of glycosaminoglycans (dermatan sulfate). It produces multiple dysostosis, corneal opacity, cardiac and respiratory alterations, and progressive functional limitation. The canine form of the Miniature Pinscher is a natural model of human MPS VI and has been used in preclinical trials of enzyme replacement and gene therapy.

Miniature Pinscher is the breed in which the canine form of MPS VI has been characterised. Carrier frequency in the breeding population is not reliably published (limited data).

- Coarse facial features («gargoylism»)
- Bilateral corneal opacity
- Bone deformities (multiple dysostosis, thickened joints)
- Kyphosis and lordosis
- Mitral and aortic insufficiency due to valvular deposition
- Hernias and short stature
- Progressive functional limitation

MPS VI was first described in humans and later in the Miniature Pinscher dog, where Berman and colleagues (2004) identified the molecular variant of the ARSB gene, formally published by Raj and colleagues in 2020. The canine model has been used in pathogenesis studies and in preclinical trials of enzyme replacement and gene therapy. A different variant of the same gene was described in the Miniature Schnauzer and a nonsense mutation in the Great Dane.

- Genotype breeding dogs before mating
- Do not mate two carriers: 25 % risk of affected homozygotes
- A carrier can be mated to a clear dog; offspring intended for breeding must be tested
- Exclude affected homozygotes from breeding
- Identify carriers in lines with a family history

Differential diagnosis with other MPS (especially MPS I and VII), with chondrodystrophy and with other bone dysplasias. Enzyme determination in leukocytes or tissue and molecular study confirm the diagnosis. Corneal and cardiac involvement usually dominate the clinical picture.

1. Raj K et al. 2020, ARSB gene variants causing Mucopolysaccharidosis VI in Miniature Pinscher and Miniature Schnauzer dogs. Anim Genet 51(6):982-986. PMID: 32985704. 2. Wang P et al. 2018, Mucopolysaccharidosis Type VI in a Great Dane Caused by a Nonsense Mutation in the ARSB Gene. Vet Pathol 55(2):286-293. PMID: 29157190. OMIA:000666-9615.