Researchers Investigate Naked Foal Syndrome in Akhal-Tekes

Researchers Investigate Naked Foal Syndrome in Akhal-Tekes

Naked foal syndrome is related to a nonsense gene variant and appears to be unique to Akhal-Tekes.

Photo: Courtesy Anina Bauer/G3

The Sphynx cat breed might have a popular following for its uniqueness as a hairless cat. But in horses, hairlessness is linked to serious health issues—and usually death. Currently limited to the Akhal-Teke breed, “naked foal syndrome” has led to the death of most known cases by 3 years of age.

In a groundbreaking study, an international group of researchers has uncovered the gene responsible for naked foal syndrome, which could help Akhal-Teke breeders eliminate the condition completely.

“We have shown that the naked foal syndrome in Akhal-Teke horses is related to a nonsense variant that we have found in a single gene on Chromosome 7, which appears to be unique to this breed among horses,” Anina Bauer, PhD student at the University of Bern, Switzerland, said at the 2017 Swiss Equine Research Day, held earlier this year in Avenches.

Mutations of the affected gene, identified as ST14, are also known to cause skin disorders in humans, said Bauer. “The association between ST14 and autosomal recessive congenital ichthyosis in humans strengthens our finding that this is the gene responsible for the condition in horses,” she said.

As a result, fellow researchers at the University of California, Davis, have developed a genetic test that allows breeders to check for the gene’s presence in their breeding stock, said Bauer. The syndrome occurs when two copies (one from each parent) of the recessive allele line up in the foal’s DNA. Horses with only one copy are carriers; they do not show outward signs but have a 25% chance of producing an affected foal if they’re bred to another carrier.

Bauer’s highly complex work has uncovered what is actually a very simple explanation for the lack of hair. The ST14 gene mutation leads to an early termination signal during the production of the ST14 protein, which is behind important functions related to skin and hair development.

A normal gene codes for a long protein. But when the mutation occurs, the gene codes for a shortened protein—it’s physically shorter than the normal protein, Bauer said. The truncated protein is probably unable to tell the hair follicles to develop as they should normally. As a result, the hair doesn’t grow and the foal is affected by naked foal syndrome.

In the study, Bauer said further research is needed to determine what leads to premature death in affected horses.

“It’s extremely important for breeders to perform this test on their horses,” Bauer said during her presentation, which won the scientific award for Best Presentation at this national research convention. “And that’s especially true when the genetic background of their breeding stock is unknown.”

The study, “A Nonsense Variant in the ST14 Gene in Akhal-Teke Horses with Naked Foal Syndrome,” was also published in G3: Genes|Genomes|Genetics

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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