Wednesday, April 18, 2012

Genes for Epilepsy found in Dogs

Researchers in Europe and the United States have identified a novel epilepsy gene for idiopathic epilepsy in Belgian Shepherds in the canine chromosome 37. Presented in the PLoS ONE journal, the findings fuel our understanding of the genetic background of the most common canine epilepsies, and provide insight into common epilepsies in humans. The study was funded in part by the LUPA ('Unravelling the molecular basis of common complex human disorders using the dog as a model system') project, which is backed under the 'Health' Theme of the EU's Seventh Framework Programme (FP7) to the tune of EUR 12 million.

A set of chronic neurological disorders characterised by seizures, epilepsy affects the lives of around 1-5% of the human population at some point in their lives. Experts say epilepsy is characterised by various syndromes, causes, prognosis and the age of patients. Based on their basic mechanisms, epilepsy syndromes are split into genetic (idiopathic) epilepsies, structural/metabolic (symptomatic) epilepsies and epilepsies of unknown cause.

Led by the University of Helsinki and the Folkhälsan Institute of Genetics in Finland, researchers from Denmark, Finland, Sweden and the United States compared the genome of dogs with epilepsy and healthy control dogs and identified a gene region in chromosome 37, which is linked to the most common form of canine epilepsy.

Up to 40% of patients with epilepsy can trace their diagnosis to genetic factors. If the specific gene region is homozygous, the risk of suffering from epilepsy is seven times greater. The researchers also suggest that other, still unknown, genetic risk factors may be present in the breed.

The type of epilepsy affecting Belgian Shepherds is very common in other breeds as well. So this discovery could improve our knowledge about epilepsies in different dog breeds.

'There are only few genes in the identified region and I believe that the ongoing analyses will help us to discover the specific epilepsy gene,' says Professor Hannes Lohi of the University of Helsinki, senior author of the study. 'This would give us a better understanding of the disease mechanisms and provide us with new diagnostic tools for the disease.'

Commenting on the study, lead author Dr Eija Seppälä of the University of Helsinki says: 'The identified genomic region is likely to be the strongest single risk factor for epilepsy in Belgian Shepherds, and we are studying an interesting gene variant causing an amino acid change in the protein level. However, this homozygous amino acid change is also present in one fifth of healthy Belgian Shepherds. The research continues in the breed and aims to identify the specific mutation for genetic testing in this loci and possibly in other chromosomes. The need for the gene test is urgent since as much as 20% of the dogs in this breed are estimated to have epilepsy.'

Idiopathic epilepsy in Belgian Shepherds appears at around three years of age.

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