DNA PROFILING & PARENTAGE
WHAT IS DNA PROFILING?
A DNA profile can be seen as a genetic fingerprint, which is unique to each animal.
The sample from the animal (hair, tissue, blood, or semen) will undergo DNA extraction, PCR amplification and then fragment analysis before the data can be analysed to produce the final result: the DNA profile report. There are various techniques to obtain a DNA profile but one of the most common and reliable methods to use, is microsatellite analysis. Microsatellites are short segments of DNA, spread throughout the genome, where the sequence of nucleotides (building blocks of DNA) repeat in the same pattern (e.g., ATATAT). This segment of DNA is fluorescently labelled, amplified, and analysed. There are two types of microsatellites present, one from the sire of the offspring and one from the dam (called alleles). The numbers present on the DNA profile certificate are the allele calls at a specific marker location. While the numbers on the report may seem fairly random, they are very useful as they vary between individuals, allowing for a unique identifier for each animal, like a fingerprint.
WHAT IS DNA PROFILING USED FOR?
A DNA profile is a unique identifier for your animal and can be used to register your animal with various regulatory bodies. It is also used for parentage verification.
PARENTAGE VERIFICATION
Parentage verification can confirm a parent-to-offspring relationship based on genetics. The DNA profile of the dam and sire will be compared to the DNA profile of the offspring, comparing the alleles that are present and that were inherited. Half of the alleles from the dam and half of the alleles from the sire will be inherited by the offspring in different combinations. This allows us to determine parentage.
MUTATION TESTING
EQUINE DWARFISM
What is dwarfism in horses?
Equine dwarfism is a condition that can either result in early abortion or foals born with physical abnormalities associated with the dwarf phenotype.
Gene Variation
Equine dwarfism is caused by four mutations in the ACAN gene. The four mutations are designated D1, D2, D3 & D4.
Breeding Implications
Normal phenotype
| D1 | D2 | D3 | D4 |
|---|---|---|---|
| WT/MUT | WT/WT | WT/WT | WT/WT |
| Normal | WT/MUT | WT/WT | WT/WT |
| WT/WT | WT/WT | WT/MUT | WT/WT |
| WT/WT | WT/WT | WT/WT | WT/MUT |
Dwarf phenotype
| D1 | D2 | D3 | D4 |
|---|---|---|---|
| WT/WT | MUT/MUT | WT/WT | WT/WT |
| WT/WT | WT/MUT | WT/MUT | WT/WT |
| WT/WT | WT/MUT | WT/WT | WT/MUT |
| WT/WT | WT/WT | WT/MUT | WT/MUT |
Lethal
| D1 | D2 | D3 | D4 |
|---|---|---|---|
| MUT/MUT | WT/WT | WT/WT | WT/WT |
| WT/MUT | WT/MUT | WT/WT | WT/WT |
| WT/MUT | WT/WT | WT/MUT | WT/WT |
| WT/MUT | WT/WT | WT/WT | WT/MUT |
It is not recommended to breed animals which carry a mutation at the D1 site, to any animals which are carriers for mutations at any other site, D2, D3 or D4. Ideally you should only cross D1 mutation carriers to animals which are clear at all other sites.
