| Contents |
|---|
| Cerebellar Abiotrophy (CA) |
| Summary |
| Understanding the Results |
| Disease Name and Genes |
| Inheritance |
Cerebellar Abiotrophy (CA)
Summary
Cerebellar Abiotrophy (CA) is an inherited neurodegenerative disease that causes neurons known as Purkinje cells, located in the cerebellum, to die off. Loss of these neurons affects balance and coordination. Symptoms typically appear between six weeks and four months of age. The symptoms include ataxia (lack of muscle control during voluntary movement, most notably affecting gait), head tremors, and lack of balance. Affected horses are often unable to rise from a reclining position. While the disease is not fatal, most owners elect to euthanize affected horses as their lack of coordination makes handling them dangerous for both the horses and handlers. There is no effective treatment.
Cerebellar Abiotrophy in known primarily in Arabian horses, where carrier rates are estimated to approach 20%.
Date of Last Update: 08/02/2016
Results
Understanding the Results
Results of the genetic test for CA are presented as shown below.
| Cerebellar Abiotrophy (CA) | ||
|---|---|---|
| N/N | Clear | This horse tested negative for CA. |
| N/CA | Carrier | Both the normal and mutant alleles are present. This horse is positive for the CA mutation but will not develop symptoms. |
| CA/CA | Affected | This horse carries two copies of the CA mutation and will develop the disease. |
Disease Name and Genes
Cerebellar Abiotrophy (CA) is caused by a C to T substitution in the upstream regulatory sequence of MUTYH, located approximately 1200 bp upstream of the start codon in a GATA-2 binding site. The substitution results in reduced levels of MUTYH mRNA.
Inheritance
Cerebellar Abiotrophy (CA) is caused by a recessive variant of the MUTYH gene. The recessive allele is commonly abbreviated as CA, with the dominant wild-type allele abbreviated as N.
Carriers of the recessive allele (N/CA) have no symptoms of the disease. If two carriers are bred, each foal has a 25% chance of having two copies of the normal allele (N/N), a 50% chance of being a carrier (N/CA), and a 25% chance of being affected (CA/CA).
If a carrier of the recessive allele (N/CA) is bred to a normal horse (N/N), each foal has a 50% chance of having two copies of the normal allele (N/N) and a 50% chance of being a carrier (N/CA).
