Bovine Progressive Ataxia (BPA), a neurodegenerative disease of the central nervous system which if affected, results in an animal’s inability to stand. As the gene is recessive, only animals with a gene from both sides of the mating will show physical signs of the condition. An animal can be a carrier and live a normal life, but if bred to another carrier can produce affected offspring. The Charolais Society monitor this gene and offer breeders an ability to test breeding stock. Most other breeds do not carry this gene so herds crossbreeding with Charolais can use a Charolais sire with the gene, but not produce affected progeny. Herds using Charolais sires over Charolais infused dams should be diligent to the status of their sire.

Inheritance Mode

Free animal x Free animal = all progeny free of the gene

Free animal over Carrier animal = 50% free progeny, 50% Carrier progeny, 0% affected

Carrier animal over Carrier animal = 25% Free progeny, 50% Carrier progeny, 25% affected progeny

Registered Charolais animals that have been tested show their status on the Animal Enquiry Search.

More information:

What is progressive ataxia?

The disease causes incoordination in Charolais cattle. The calves are born clinically normal. Onset of the disease is typically seen at 18-24 months-of-age. Early onset cases have been reported for animals as young as 8 months old and some cases have been reported for animals who are 30 months-of-age at onset, but these reports are infrequent. Affected cattle are typically culled by 36 months-of-age. French surveys determined no genotyped cattle older than 30 months-of-age were homozygous for the variant allele. Incoordination is first noticeable in the rear limbs which can exhibit spastic movements. Weaving, stumbling, and toe dragging are common. Affected cattle may have difficulty getting up and as front legs get affected, they can become unable to rise. Females may experience pulsating urination. Progression takes several weeks to a few months.

The disease is caused by a single substitution, c.608G>A, in the KIF1C gene. This results in an amino acid substitution in a highly conserved region of the gene. A splicing defect occurs during transcription and the result is absence of the KIF1C protein in the brain. This protein is important in cytoplasmic structure and transport in the cells that form myelin in the brain and spinal cord. Myelin is the insulating wrap created by cells called oligodendroglia that wrap around nerve fibers and regulate signal movement along nerve pathways. To be affected, a calf must be born homozygous for the variant allele. Both parents must have the variant allele for the calf to be affected.

Further Reading: Click here