UNDERSTANDING GENETIC CONDITION RESULTS (INCLUDING GENEPROB)
The Australian Wagyu Association (AWA), in collaboration with its genotype laboratory partners, provides genetic testing options to determine the status of Wagyu animals for a range of known deleterious genetic conditions. This article outlines these conditions and explains how to interpret results to support effective breeding decisions.
WHAT GENETIC CONDITIONS OCCUR IN WAGYU ANIMALS?
Research has identified several recessive inherited genetic conditions in Wagyu cattle. The key conditions include:
Spherocystosis (B3) – A disorder affecting the membrane of red blood cells (erythrocytes). The B3 gene is essential for maintaining cell structure. Animals with two copies of the mutation develop severe anaemia due to abnormal red blood cells, with most affected calves dying within the first week of life. In rare cases, animals may survive longer but exhibit significant growth retardation.
Chediak–Higashi Syndrome (CHS) – An immune system disorder affecting macrophages (white blood cells critical for disease response). Affected animals have reduced ability to fight infections and may exhibit prolonged bleeding. An early sign is excessive bleeding from the umbilical cord at birth, often accompanied by a pale coat colour.
Claudin 16 Deficiency (CL16) – Also known as renal tubular dysplasia (RTD), this condition affects kidney function and leads to progressive kidney failure. Symptoms can appear from late adolescence, and affected animals typically do not live beyond six years of age.
Factor XI Deficiency (F11) – A blood clotting disorder resulting in prolonged bleeding after injury or surgical procedures. Unlike other conditions, F11 is generally non-lethal, and affected animals can survive and reproduce. However, carrier-to-carrier matings may be associated with reduced fertility or embryonic survival.
IARS Disorder – Caused by a mutation affecting protein synthesis, this condition results in late-term abortion or weak calves that die shortly after birth. Affected calves often display anaemia, weakness, poor growth, and increased susceptibility to infection.
Annexin A10 (A10) – A condition associated with early embryonic loss. Mutations in the Annexin A10 gene disrupt key cellular processes, contributing to reduced reproductive efficiency in affected herds.
Factor XIII Deficiency (F13) – A recessive disorder that impairs stable blood clot formation, leading to excessive bleeding. Affected calves may suffer internal haemorrhaging, weakness, or sudden death at a young age. Carrier animals appear normal but can transmit the condition. The frequency of F13 in the AWA population is considered low.
WHAT IS GENEPROB?
GeneProb* is a predictive tool that estimates the likelihood (expressed as a percentage) that an animal carries a recessive genetic condition. These estimates are based on pedigree information and available test results, providing valuable insight for animals that have not been directly tested. GeneProb analyses are updated weekly, with revised results published each Friday.
Currently, GeneProb is calculated for B3, CHS, CL16, F11, IARS and ANX10. Results are only displayed for animals without a direct laboratory test.
* http://www-personal.une.edu.au/~bkinghor/geneprob.htm) based on the method of Kerr, R.J. and Kinghorn, B.P. 1996. An efficient algorithm for segregation analysis in large populations. J. Anim. Breed. Genet. 113:457-46 https://doi.org/10.1111/j.1439-0388.1996.tb00636.x
HOW ARE GENETIC CONDITION RESULTS REPORTED?
Genetic condition results (from the laboratory or Geneprob) are displayed through the AWA Helical interface using a standard coding format (figure 1 and figure 2). Each code includes the condition identifier (e.g. B3, F11) followed by a suffix indicating the result:
| Result Code | Description |
| _ _ F | Free – Tested and confirmed free of the mutation (homozygous normal) |
| _ _ C | Carrier – One copy of the mutation present (heterozygous) |
| _ _ A | Affected – Two copies of the mutation present (homozygous recessive) |
| _ _ #% | Estimated probability of being a carrier (untested animal) |
| _ _ FU | Expected to be free based on pedigree, but not directly tested |
Figure 1 – Example individual animal genetic condition results, based on Geneprob, on the AWA Helical database.
Figure 2 – Example individual animal genetic condition results, based on laboratory result, on the AWA Helical database.
WHAT HAPPENS IN TWO CARRIER ANIMALS ARE MATED?
Animals with only one copy of the undesirable gene and one copy of the normal form of the gene (i.e. generally with no symptoms), are known as “carriers”. A carrier will, on average, pass the undesirable gene form to an arbitrary 50% of their progeny.
If a carrier bull and carrier cow are mated the three outcomes may be:
- There is a 25% chance that the progeny will have two normal genes, will not be affected by the condition and will not pass on the undesirable gene.
- There is a 50% chance that the mating will produce a carrier.
- There is a 25% chance that the progeny will inherit two copies of the undesirable gene and hence be affected by the genetic condition.
When a carrier animal is mated to an animal tested free of the genetic condition, three outcomes are possible:
- All progeny will appear normal and will be generally unaffected by the condition.
- There is a 50% chance that the mating will produce a carrier.
- There is a 50% chance that the progeny produced will have two normal genes and so will not pass on the undesirable gene.
Importantly, animals confirmed as free through DNA testing will not pass the mutation to their offspring, even if carriers appear in their pedigree.
Figure 3 – Possible mating outcomes from different mating combinations for a single gene recessive genetic condition
SUPPORT
For further information or assistance interpreting genetic condition results, please contact the Australian Wagyu Association.