First reported case of fragile foal syndrome type 1 in the Thoroughbred caused by PLOD1 c.2032G>A.
Authors: Grillos Alexandra S, Roach Jessica M, de Mestre Amanda M, Foote Alastair K, Kinglsey Nicole B, Mienaltowski Michael J, Bellone Rebecca R
Journal: Equine veterinary journal
Summary
# Editorial Summary: Fragile Foal Syndrome Type 1 in Thoroughbreds Fragile Foal Syndrome Type 1 (WFFS) has historically been confined to Warmblood breeds and attributed to a recessive mutation in the PLOD1 gene (c.2032G>A), which encodes an enzyme essential for collagen cross-linking; this case report documents the first confirmed occurrence of the same genetic variant in a Thoroughbred, expanding our understanding of breed susceptibility. The research team identified the homozygous PLOD1 mutation in an affected foal presenting with the characteristic clinical signs of WFFS—including hyperextensible, fragile skin and mucous membranes that tear easily, poor wound healing, and connective tissue fragility. The identification of this autosomal recessive condition in a Thoroughbred carries significant implications for breeding programmes, as carrier screening of parents could prevent affected foals; both sire and dam must be carriers or affected for a foal to develop the syndrome, meaning genetic testing of breeding stock is now warranted across breed boundaries. Veterinarians and stud managers should be alert to the possibility of WFFS in any foal presenting with unexplained skin fragility and poor wound healing, regardless of breed, and consider PLOD1 mutation screening in suspected cases to enable informed breeding decisions and prevent future affected foals.
Read the full abstract on PubMed
Practical Takeaways
- •WFFS is no longer breed-specific; veterinarians should consider PLOD1 mutation testing in Thoroughbreds presenting with fragile foal phenotype, not just warmbloods
- •Genetic counseling and carrier testing become relevant for Thoroughbred breeding programs to prevent autosomal recessive disease transmission
- •This case expands understanding of disease prevalence across breeds and may warrant updated screening protocols in Thoroughbred registries
Key Findings
- •First reported case of Warmblood Fragile Foal Syndrome Type 1 (WFFS) in a Thoroughbred breed
- •PLOD1 c.2032G>A (p.Gly678Arg) mutation identified as causative variant in Thoroughbred, previously only documented in warmbloods
- •Autosomal recessive inheritance pattern confirmed with similar genetic mechanism across different horse breeds