Fragile foal syndrome type 1 in horses in Ireland, and industry perspectives on equine genetic testing

The completion of the equine reference genome has led to significant advancements in our understanding of equine genetics and has paved the way for a better understanding of equine disease and athletic performance. Numerous genetic tests are now available for disease and performance traits in horses. Fragile Foal Syndrome Type 1 (FFS1) recently emerged as a fatal collagen disorder caused by a variant of the equine procollagen lysine 2-oxoglutarate 5-dioxygenase 1 (PLOD1 c.2032G>A, p.Gly678Arg) gene. In this study, we investigated the frequency of the PLOD1 variant in sport horses and Thoroughbreds in Ireland. Hair samples were collected from sport horses and Thoroughbreds, and in-house and commercially available polymerase chain reaction (PCR) tests were used to distinguish between samples that were heterozygous, homozygous wild-type, and homozygous for the PLOD1 variant (c.2032G>A, p. Gly678Arg). The study revealed a low carrier frequency of the PLOD1 variant in sport horses (1.98%, 95% CI, Wilson score: 0.91% - 4.25%) and Thoroughbreds (2.75%, 95% CI, Wilson score: 0.94% - 7.78%). This research also documents the first recognised clinical case of FFS1 in Ireland, the second case reported in the Thoroughbred breed. Due to the reluctance encountered from horse owners during the above research project to engage in genetic testing, we conducted a survey to investigate the attitudes, knowledge, and practices regarding genetic testing among equine industry stakeholders, including veterinarians. A questionnaire was created using Qualtrics software, which included six domains (demographics, attitudes toward genetic testing, the use of genetic testing, genetic knowledge, barriers to the use of genetic testing, and future enablers). Chi-squared tests were performed to determine statistical associations between stakeholder demographics and responses in each of the other 5 domains. Post-hoc analysis was performed when the omnibus test was statistically significant. For post-hoc testing, the alpha level was adjusted with the sequential Benjamini-Hochberg procedure. The study identified overall positive attitudes towards genetic testing; however, regional and breed differences were identified. Stakeholders involved in the Thoroughbred sector and those based in Ireland and Northern Ireland had less positive attitudes, poorer awareness of genetic disease and were less likely to have performed genetic testing. A positive association was identified between genetic knowledge and the use of genetic testing by industry stakeholders and veterinarians. Increased industry awareness and education will be key to realising the full benefits of genetic testing within the equine industry.