Breeds Affected: Arabian horses and related breeds
Samples Accepted: Blood, Hair
Disease Information: Cerebellar Abiotrophy (CA) is also known as Cerebellar Cortical Abiotrophy (CCA). Foals born with this disease appear normal, but the death of cells in the cerebellum can lead to clinical symptoms as early as six weeks of age. CA affects balance and coordination, but because the disease varies in severity, some animals may not be diagnosed until later in life.
The possible genotypes are:
N/N The horse is normal, and cannot produce CA-affected offspring.
N/ca The horse is a carrier of CA, and can pass the allele on to approximately 50% of any offspring. If bred to another N/ca carrier, approximately 25% of the offspring will be normal, 50% will be carriers, and 25% will be affected.
ca/ca The horse is affected with CA. If bred to a normal animal, 100% of the offspring will be carriers. If bred to a N/ca carrier, 50% of the offspring will be carriers and 50% will be affected.
– Carriers may be bred to normal animals (N/ca x N/N) without any risk of producing affected offspring. The offspring should also be tested before breeding to determine if they are carriers or normal.
– Breeding two carriers (N/ca x N/ca) is not recommended due to the possibility of 25% of the offspring being affected.
– Affected animals (ca/ca) should not be used for breeding.
Inheritance Information: Animals which have two copies of this allele are affected with CA, and animals with one copy are clinically-normal carriers.
Test Information: This mutation test identifies a single base pair change in exon 4 of the TOE1 gene.
Brault, L.S., Cooper, C.A., Famula, T.R., Murray, J.D. and Penedo, M.C.T. (2010) Mapping of equine cerebellar abiotrophy to ECA2 and identification of a potential causative mutation affecting expression of MUTYH. Genomics doi: 10.1016/j.ygeno.2010.11.006.
Further information is available at the Online Mendelian Inheritance in Animals website.