CA is a neurological disorder that affects coordination and balance
Breeds known to be affected
Arabian and related breeds, Welsh Pony
CA is a neurological disorder that affects the cells in the cerebellum, the part of the brain that is important for motor control and co-ordination. CA causes head tremors, ataxia and other effects. Affected horses are more prone to falling and are generally not safe enough to ride, so are usually euthanised. Symptoms generally appear from 6 weeks to around 4 months old.
CA has been linked to a mutation in the TOE1 gene and is a recessive disorder, meaning that a horse needs to be homozygous (CA/CA) to show symptoms. If a horse is a carrier (n/CA), it will not show any clinical signs of CA. However, there is a 50% chance it will pass the variant to its offspring, so mating to other carriers should be avoided to prevent the birth of an affected foal.
This particular CA mutation has been identified primarily in Arabians, but also at low frequencies in Welsh Ponies and some other breeds.
Interpretation of results
n/n: Horse does not carry the mutation associated with CA.
n/CA: Horse has one copy of the mutation associated with CA.
CA/CA: Horse has two copies of the mutation associated with CA.
Brault et al. Mapping of equine cerebellar abiotrophy to to ECA2 and identification of a potential causative mutation affecting expression of MUTYH. Genomics 2011; 97:121-129 doi:10.1016/j.ygeno.2010.11.006