29/10/2025
Equine Genetics 101: Sunshine (SUN) ☀️🐴
In 2019, Etalon Genetics identified the Sunshine (SUN) mutation in a TWH x Standardbred stallion named Captain Sunshine. This recessive mutation adds to our understanding of the SLC45A2 gene, the same dilution gene behind Cream (CR), Pearl (PRL), and Snowdrop (SNO).
What does Sunshine (SUN) do? The mutation affects pigment deposition in the coat, skin, and eyes, creating lighter or unusual color variations. Similar to Pearl (PRL), the Sunshine (SUN) mutation will appear “invisible” on its own, but when paired with another dilute mutation on the SLC45A2 gene such as Cream (CR), it gives the effect of a double dilute (i.e. cremello, perlino)! Sunshine (SUN) can mimic the appearance of other dilutions, making genetic testing the only way to confirm if a horse carries the mutation.
While the full effects of Sunshine (SUN) are still being studied, so far there are no health concerns associated with this mutation. The Sunshine (SUN) mutation has only been found in a small number of horses related to Captain Sunshine at this time. The mutation could be generations old or newer, since Cream (CR) that helped this variant shine isn't a variant typically found in Standardbreds, it could have hidden for quite a long time! Research is ongoing, and owners of horses with unusual dilute appearances are encouraged to test and join the study.
Curious if your horse carries Sunshine (SUN)? Etalon’s genetic testing will help you know for sure!
🧬 Shop testing here: https://etalondx.com/horse-dna-tests/
🔬 Learn more about Sunshine here: https://etalondx.com/news-media/sunshine-mutation
📖 Read the official paper here: https://doi.org/10.1111/age.12790