Mucopolysaccharidosis I (Boston Terrier Type)

Other Names: Alpha-L-iduronidase deficiency, Hurler syndrome, Scheie syndrome, MPS I
Affected Genes: IDUA
Inheritance: Autosomal Recessive
Mutation: chr3:92143164 (canFam4): -/GGGGGCCG
Breed(s): Boston Terrier

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Common Symptoms

Mucopolysaccharidosis I (Boston Terrier Type) is an inherited Lysosomal Storage Disorder. Affected dogs have insufficient activity of the Enzyme alpha-L-iduronidase, which is responsible for breaking down glycosaminoglycans (GAGs). GAGs are an important component of tissues throughout the body. In affected dogs there is an accumulation of breakdown products in cells causing abnormal growth and function of many different organ systems. Affected dogs typically present around 12 months of age with signs of neurological disease including Ataxia and abnormal mentation. Other features of this disease include joint laxity, abnormal head shape, cloudy eyes, and a large liver. Affected dogs are often humanely euthanized due to disease progression.

Testing Tips

Genetic testing of the IDUA gene will reliably determine whether a dog is a genetic Carrier of Mucopolysaccharidosis I (Boston Terrier 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 IDUA 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

  • Dierenfeld AD, McEntee MF, Vogler CA, Vite CH, Chen AH, Passage M, Le S, Shah S, Jens JK, Snella EM, Kline KL, Parkes JD, Ware WA, Moran LE, Fales-Williams AJ, Wengert JA, Whitley RD, Betts DM, Boal AM, Riedesel EA, Gross W, Ellinwood NM, Dickson PI. Replacing the enzyme alpha-L-iduronidase at birth ameliorates symptoms in the brain and periphery of dogs with mucopolysaccharidosis type I. Sci Transl Med. 2010 Dec 1;2(60):60ra89. [PubMed: 21123810]
  • Mansour TA, Woolard KD, Vernau KL, Ancona DM, Thomasy SM, Sebbag L, Moore BA, Knipe MF, Seada HA, Cowan TM, Aguilar M, Titus Brown C, Bannasch DL. Whole genome sequencing for mutation discovery in a single case of lysosomal storage disease (MPS type 1) in the dog. Sci Rep. 2020 Apr 16;10(1):6558. [PubMed: 32300136]
  • Menon KP, Tieu PT, Neufeld EF. Architecture of the canine IDUA gene and mutation underlying canine mucopolysaccharidosis I. Genomics. 1992 Nov; 14(3):763-8. [PubMed: 1339393]
  • Shull RM, Helman RG, Spellacy E, Constantopoulos G, Munger RJ, Neufeld EF. Morphologic and biochemical studies of canine mucopolysaccharidosis I. Am J Pathol. 1984 Mar;114(3):487-95. PubMed PubMed: 6320652 [PubMed: 6320652]
  • Shull RM, Munger RJ, Spellacy E, Hall CW, Constantopoulos G, Neufeld EF. Canine alpha-L-iduronidase deficiency. A model of mucopolysaccharidosis I. Am J Pathol. 1982 Nov;109(2):244-8. PubMed: 6215865 [PubMed: 6215865]
  • Spellacy E, Shull RM, Constantopoulos G, Neufeld EF. A canine model of human alpha-L-iduronidase deficiency. Proc Natl Acad Sci U S A. 1983 Oct;80(19):6091-5. PubMed: 6412235 [PubMed: 6412235]