Neuronal ceroid lipofuscinosis 4A (NCL4A) is an adult-onset, lysosomal storage disease affecting dogs. NCL4A is caused by deficiency in the activity of the Enzyme arylsulfatase G (ARSG), which is necessary to break down certain proteins in the cells. As a result there is an accumulation of these compounds in cells, which affects the normal function of the brain and nervous system. Affected dogs present between 3 to 5 years of age with slowly progressive neurologic disease. Symptoms include a lack of muscle coordination, tremors, abnormal eye movement, abnormal gait and difficulty in balancing and jumping. Dogs are often euthanized 2 to 4 years after initial disease symptoms when they can no longer walk. Rarely affected dogs can live a normal lifespan with mild symptoms.
Genetic testing of the ARSG gene will reliably determine whether a dog is a genetic Carrier of neuronal ceroid lipofuscinosis 4A. Neuronal ceroid lipofuscinosis 4A 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 ARSG gene mutation. Reliable genetic testing is important for determining breeding practices. Because symptoms may not appear until adulthood, genetic testing should be performed before breeding. 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.
Abitbol M, Thibaud JL, Olby NJ, Hitte C, Puech JP, Maurer M, Pilot-Storck F, Hédan B, Dréano S, Brahimi S, Delattre D, André C, Gray F, Delisle F, Caillaud C, Bernex F, Panthier JJ, Aubin-Houzelstein G, Blot S, Tiret L. A canine Arylsulfatase G (ARSG) mutation leading to a sulfatase deficiency is associated with neuronal ceroid lipofuscinosis. Proc Natl Acad Sci U S A. 2010 Aug 17; 107(33):14775-80.