Genetics

Genetic Conditions

Genetic Conditions

PA Policy as of 9/1/24

Donor dams and AI sires born after January 1, 2020 are required to be tested for Bovine Progressive Ataxia (BPA), prior to the registration of progeny and/or additional progeny. Animals that have a 100K DNA result on file, will only need to have the BPA test added to their profile. Animals without a 100K on file, will need to have the 100K and BPA ran.

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GENETIC CONDITIONS FAQS

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. Initial symptoms can be similar to rabies, other infections or an injury. Infections progress faster and injuries are generally static or injured animals slowly recover.

What is the cause of progressive ataxia?

The disease is caused by a single substitution, c.608G>A, in the KIFlC 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. The absence of this protein disables maintenance of the myelin and accumulation of cellular materials in the oligodendroglia forming plaques in the brain and spinal cord. Pathologists can recognize these plaques microscopically for diagnosis. The abnormal myelin leaves some nerve fibers exposed and changes nerve conduction by changing myelin structure. 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. A genotypic affected, but preclinical bull could produce a high number of carriers and more frequent affected offspring when mated to a normal and a carrier heifer respectively.

TEST RESULTS

BPA (Bovine Progressive Ataxia) results for tests completed at Neogen (GeneSeek) can be viewed by the owner of an animal in the AICA Online Registry System in the breeder's Lab Results page as BPA Results or under the Charolais Search under Lab Results. The AICA will note animals to be progressive ataxia free - PAF, progressive ataxia carrier - PAC, or progressive ataxia affected - PAA. Paper copies of Neogen lab results are available from the registration department upon request.

TESTING REQUIREMENTS

PA testing is voluntary, except for Donor dams and AI sires born after January 1, 2020 are required to be tested for Bovine Progressive Ataxia (BPA).

DNA Sampling with AICA at Neogen

Request DNA kits in the AICA Online Registry System or by contacting the registration department. Request addition of the BPA (Bovine Progressive Ataxia) test when ordering the DNA kit. DNA samples may include tissue sampling units (TSUs), blood cards, semen or hair. DNA kits (forms) are specific to the animal being tested. More information here.

Sample paperwork rewrite

Animals with 100K Genotype Results at AICA

If DNA of an owned animal was processed at Neogen (GeneSeek) after September 1, 2020, a BPA test can be requested by the owner by contacting the AICA registration department by phone or email.

Animals with 50K Genotype Results at AICA

Animals with genotypes submitted to AICA prior to September 1, 2020 will need 100K genotype results for the BPA test. A new sample must be submitted by the owner of the animal. Request addition of the BPA test when ordering the DNA kit. Estimated processing time at Neogen is 3-4 weeks upon receipt of the sample.

Additional lab available for PA testing Charolais cattle

In October of 2022, a third lab became available for testing Charolais cattle for Progressive Ataxia. This lab is called Gene Check and it is in Greeley, CO. To order testing materials, you may call the lab at the following toll-free number: (970) 472-9951. The cost per sample is $20 and the lab offers a three to five day turn around
PA testing results from Gene Check & UC Davis are not parent verified.

How can I test my breeding stock?
If your bulls or females have been genotyped on Neogen's 100K chip, the PA status of the animals may be available now. Please contact Maggie Smithee at AICA for instructions on how to proceed. There is also a stand-alone test at the UC-Davis Genetics Lab. The test requires a DNA source such as: a small piece of tissue, 20 hairs plus roots, or blood collected in an EDT A (purple top) tube. Each lab has a preference for how they receive DNA. Please refer to their website for sampling and submitting instructions.

UC-Davis reports animal genotype as normal - NN, Carrier - NA, or homozygous for the variant - AA. The AICA will note animals to be progressive ataxia free - PAF, progressive ataxia carrier - PAC, or progressive ataxia affected - PAA. If affected animals are sampled at a young age, they may be preclinical and appear normal. The ability to test will allow breeders to segregate this undesired trait from the many good attributes of high valued females or bulls by selecting PAF offspring from PAC or PAA sires or dams.

How is progressive ataxia passed down, and what does it mean if my animal is a carrier of the variant?
Progressive ataxia is an autosomal recessive trait. This means for an animal to be affected, or to express the phenotype, they must be carrying two copies of the variant.

Gender is not relevant in the examples shown above and can be reversed in these examples. Carriers were found in one study to have good muscling. Their use in a terminal crossing situation may have merit as a salvage step. Offspring from three of these scenarios will result in some normal calves who are non-carriers and thus, can be tested free and utilized to capture other good traits from a desirable genetic line.

Mating	Phenotype	Variant carrier status
Normal bull mating a normal cow	all calves are normal	normal calves - non-carriers
Carrier bull mating a normal cow	all calves are normal	½ calves are carriers ½ are non-carriers
Carrier bull mating a carrier cow	¼ affected ¾ normal	¼ non-carriers and ½ offspring are carriers
Affected bull mating a normal cow	all calves are normal	all calves are carriers
Affected bull mating a carrier cow	½ affected ½ normal	all normal calves are carriers
Affected bull mating an affected cow	all calves are affected	all calves are affected with both variants

Genetics

Genetic Conditions

Genetic Conditions

PA Policy as of 9/1/24

Downloads

GENETIC CONDITIONS FAQS

What is progressive ataxia?

What is the cause of progressive ataxia?

TEST RESULTS

TESTING REQUIREMENTS

DNA Sampling with AICA at Neogen

Animals with 100K Genotype Results at AICA

Animals with 50K Genotype Results at AICA

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