Another New White Gene

Working in the world of genetics, there is never a moment to rest. Over the past several years, there has been an explosion of genomic data and new discoveries that have taken what we thought we knew and turned it all upside down. Here at EtalonDx, there has been no shortage of exciting new discoveries over the past several years as we explore the world of equine genetics with a brilliant staff of researchers. And, excitingly enough, we have just recently discovered a brand-new genetic mutation that we are excited to share.

Meet the beautiful Aghilasse and his adorable son Kairaan. These two are spectacular Barb horses owned by our dear friend, Ghislaine, out of France. Ghislaine reached out to Etalon to get to the root of what was causing their incredible white coat, and the answer was not what anyone expected! Barb horses are best known for their gentle and willing nature. These horses originated from North Africa and are desert horses, much like an Arabian.

When performing DNA sequencing on both horses, EtalonDx researchers made a shocking discovery: a brand-new mutation in the same location as a prior, rare mutation that is believed to be the cause of their spectacular white coats.

Aghilasse’s Variant Summary: aa, ee, + NEW mutation Kairaan’s Variant Summary: aa, ee, nd1/nd2, NEW mutation

At this point, we know that:

• These horses have a lovely white coat and no known genetics to match prior to this discovery
• Neither the sire nor the foals have any reported health effects
• They are beautiful and it is our privilege to study them (thank you Ghislaine!!)

Scientific Details to Date: This novel mutation is located within the “KIT” gene. The surprising part of the discovery is not that it is a “new” mutation, but that it is actually a “third” variant of a previously reported Dominant White mutation! That means it’s in the same genomic location as a prior reported allele, yet, this new Dominant White leads to a different amino acid change than the previous one. What the heck?? Read on Nerd Herd…

After discovering this novel mutation, pinning down its precise place and base pair change, our job now is to analyze the amino acid change and figure out how it impacts the protein structure and function. One thing we already suspect is that the mutation in this case results in the depopulation of melanocytes (if you don’t have melanocytes, you don’t have any way to produce pigment!) Something we don’t know yet, is if it’s harmful in multiple copies. This begs the question, “Would a homozygote of this mutation be alive and well?” The answer is simply, “We don’t know yet.” We don’t know, not only because this horse has limited offspring, but also because we haven’t yet completed our research.

To confirm our suspicions we’ll need to computationally predict the normal or reference protein secondary and tertiary structures (because they may not be known in horses) and compare them to the novel mutation to see how they differ. We also utilize specialized software that predicts if the amino acid change has an impact on the biological function of the protein. What we are getting at here is simply, “what is it and what does it do in comparison to what we already know?”

Once all of this hard work is completed, the fun part begins: What do we call it and how many of our beloved horses might have it? That’s where you come in! Stay tuned for more information on this as we sort out what is known, what we found, where it may have come from and what the heck we call it! Right now the likely name will be W28, W29 or W30 (because we just don’t know yet what others have been busy finding so we don’t want to step on their toes without checking what they called their new KIT whites.)

Visit Ghislaine at www.facebook.com/rislainepoint to learn more about her and her beautiful horses!

Update: September 23rd, 2020

We are calling it W30... maybe! Scientific predictive modeling indicates that 2 copies inherited (homozygote) might be lethal... but it is still unknown. Stay tuned for more details and updates as we journey through the discovery and publication process!

Update: November 5th, 2020

Publication on new novel white W30 gene titled "De novo mutation of KIT causes extensive coat white patterning in a family of Berber horses" has officially been published by Team Etalon researchers! We are thrilled at this latest update and discovery. Access the publication by clicking the link below: https://onlinelibrary.wiley.com/doi/10.1111/age.13017