Overview
Hereditary Labrador Encephalopathy (HLE) in a novel, genetic neurodegenerative disease, caused by a recessive mutation that segregates in the Labrador retriever breed.
Clinical signs appear before 1 year of age and include fearful/agitated panic-like episodes and seizures, with dogs appearing normal between episodes. There is some overlap between the clinical signs of HLE and idiopathic epilepsy, a different neurological disease that Labrador Retrievers are also predisposed to, and in some cases HLE might be misdiagnosed as idiopathic epilepsy. Dogs affected with HLE are responsive to treatment with anti-epileptic medication and the disease does not appear to be progressive. This DNA test can be used to aide differential diagnosis of Labradors suspected to be affected with idiopathic epilepsy or HLE.
The variant in the gene that causes Hereditary Labrador Encephalopathy in Labrador Retriever is autosomal recessive. This means that dogs that carry two copies of the variant (homozygotes) will almost certainly develop Encephalopathy during their lives. Dogs that carry a single copy of the variant (also known as carriers or heterozygotes) will not develop Encephalopathy as a result of the variant, but they will pass the variant onto about half of any offspring they have. Breeding dogs that will not develop Encephalopathy should be the breeder’s priority, with a reduction in variant frequency within the whole breed being the secondary, longer-term target.
Carriers can be bred from safely, provided they are mated to a dog that has also been tested and is clear of the variant (i.e. carry no copies of the variant). If a carrier is mated to a clear dog approximately half of the resulting puppies will also be carriers, so should be tested themselves prior to breeding. Breeding carriers to tested, clear dogs is safe, in terms of avoiding dogs affected with Hereditary Labrador Encephalopathy, and will help to maintain the genetic diversity of a breed. It is therefore encouraged, particularly in the first few generations following the availability of a new genetic test, so that other desirable characteristics and traits can be preserved before the frequency of the disease variant within the breed is gradually reduced.
