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Published: 28 April 2014

New gene breakthrough for dog disease research

Study uncovers potential gene that could be key to understanding the development of canine Chiari malformation - an inherited condition that causes dogs to have brains that are too big for their skulls.

Chiari malformation (CM) affects many toy dog breeds which have been bred to have attractive baby–like heads, including the Cavalier King Charles spaniel and the Chihuahua.  It can cause headaches, problems with walking or even paralysis. Humans can be affected by a similar condition (called CMI) when certain skull bones fuse too early causing the cerebellar tonsils of the brain to descend through an opening in the base of the skull.

Dr Clare Rusbridge, Reader in Veterinary Neurology, is leading pioneering research into this complex genetic condition in collaboration with colleagues from the University of Montreal and the University of Georgia.  Read about the team’s previous research which identified the specific effect Chiari malformation has on the shape of a dog’s skull and brain. 

Their latest study, published in the journal PLOS One,  involved linking two types of information – phenotypic data (trait measurements) and genotypic data (usually molecular markers) – in an attempt to explain the genetic basis of variation in CM. The project was funded by  Canadian Institutes for Health Research.

A total of 14 quantitative skull, brain and vertebrae measurements were taken from 155 Griffon Bruxellois and tested for association to CM.  Six traits were found to be associated to CM and were subjected to a whole-genome association study.  This identified two novel genomic regions that were strongly associated to CM in the dog. 

Dr Rusbridge said, “One genomic region contains an excellent candidate gene called Sall-1. Sall-1 is involved in development of the skull, and in humans the equivalent gene is mutated in Townes-Brocks syndrome which has previously been associated to CMI. The team is very excited by this finding. Not only may it help dogs and breeders, but it might also help improve understanding of the condition in humans and lead to improved diagnosis and treatment options.”

Following this breakthrough, the University of Surrey has been awarded a £138,500 grant from the Dogs Trust to repeat this approach in the Cavalier King Charles spaniel breed with a view to finding a genetic cause for both painful CM and Syringomeylia, a condition that occurs when spinal fluid collects inside the spinal cord.

Find out more about canine CM and learn more about the human condition on the Ann Conroy Trust website

You can watch how the brain changes shape from a normal Griffon Bruxellois to one with Chiari malformation and Syringomyelia on YouTube.

Find out more about Veterinary Medicine and Science programmes and research at Surrey.