Common Symptoms
Globoid cell leukodystrophy (Irish setter type) is an inherited Lysosomal Storage Disorder affecting Irish setters. Affected dogs are normal at birth but at about 3 to 6 months of age, these dogs show signs of muscle weakness and uncoordinated movement. Affected dogs have a deficiency of the Enzyme galactocerebrosidase which is responsible for breaking down Myelin in the nervous system. As a result, there are abnormal accumulations of fatty myelin bi-products that affect the ability of certain nervous cells to make myelin. Symptoms include crossing legs while walking, widely spaced stance, jerky movements, high stepping and body tremors. Overall muscle tone is decreased and reflexes are decreased or absent. As the disease progresses, blindness, paralysis and death can occur.
Breed-Specific Information for the Irish Setter
The Mutation of the GALC gene associated with globoid cell leukodystrophy (Irish setter type) has been identified in Irish setters, although its overall frequency in this breed is unknown.
Testing Tips
Genetic testing of the GALC gene in Irish setters will reliably determine whether a dog is a genetic Carrier of globoid cell leukodystrophy (Irish setter type). Globoid cell leukodystrophy (Irish setter type) 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 GALC 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. Irish Setters 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
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Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA [internet]. AFIP Wednesday Slide Conference - No. 2 ; Case IV - 98A-2995 (AFIP 2641931) 9 September 1998 [cited 23 Dec 2013] Available at http://www.askjpc.org/wsco/wsc/wsc98/98wsc02.htm.
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McGraw RA, Carmichael KP. Molecular basis of globoid cell leukodystrophy in Irish setters. Vet J. 2006 Mar; 171(2):370-2.
[PubMed: 16490723]
