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Breeds: Akhal-Teke, Akhal-Teke Cross, Mixed Breed, Unspecified
Description
Naked Foal Syndrome (NFS) is a rare inherited skin disorder found in the Akhal-Teke breed. Affected foals are born with almost no body, mane, or tail hair and show a mild ichthyosis, along with dry, scaly skin, abnormal teeth development, digestive problems including persistent diarrhea, and laminitis-like signs.
The condition is caused by a nonsense variant in the ST14 gene, ST14:c.388G>T (p.Glu130*), which introduces a premature stop that truncates more than 80% of the gene’s open reading frame. ST14 is involved in the signaling that drives hair growth in the skin. In humans, variants in the same gene are responsible for an autosomal recessive form of congenital ichthyosis.
The first records of hairless Akhal-Teke foals date back to 1938. Affected foals often die within days to months of birth, though some have survived to around three years of age; the specific cause of these early deaths is not well understood. The Akhal-Teke studbook has been closed since 1932, and the resulting limited gene pool and line breeding have favored the spread of the variant through the population.
NFS is inherited as a monogenic autosomal recessive trait, so a foal must inherit two copies of the variant to be affected. Carriers have one copy and show no signs of disease. If two carriers are bred, each foal has a 25% chance of being affected and a 50% chance of being a carrier. Given the breed’s small population, carriers need not be removed from the breeding pool; a carrier bred to a clear horse will never produce an affected foal, so DNA testing allows breeders to preserve genetic diversity while avoiding affected foals.
Possible results
| Genotype | Description |
|---|---|
| NFS/NFS | Affected: Horse has two copies of the NFS variant and is expected to develop signs of the disorder. |
| n/NFS | Carrier: Horse has one copy of the NFS variant and is not expected to show signs of the disorder. Each offspring has a 50% chance of inheriting the variant. |
| n/n | Clear: Horse does not carry the NFS variant and cannot pass it on to offspring. |
Breeds Affected
Akhal-Teke, Akhal-Teke Cross
Reference
A Nonsense Variant in the ST14 Gene in Akhal-Teke Horses with Naked Foal Syndrome.
[PMID: 28235824]