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Fragile Foal Syndrome (FFS)
| Acronym: | FFS |
| Gene: | PLOD1 |
| Mutation: | c.2032G>A |
| Inheritance: | Autosomal Recessive |
| Sample type: | WBE (Whole Blood EDTA), HA (Hairs - with roots) |
Genetics and characteristics
Fragile Foal Syndrome (FFS) is an inherited connective tissue disease that affects several breeds of horses. Horses with FFS have skin hypersensibility, incomplete closure of the abdominal wall, hyperextension of joints, scoliosis, muscle hypotonia, which makes them unable to stand and breathe properly. FFS is caused by a genetic mutation in the procollagen-lysine, 2-oxoglutarate 5-dioxygenase 1 (PLOD1) gene responsible for making an enzyme that modifies lysine, one of the building blocks to make proteins. The mutation in a single nucleotide of the FFS gene inhibits the hydroxylation of lysine in the production of collagen, which is a complex molecule that provides strength and support to many connective tissues.
FFS is inherited as an autosomal recessive disease, therefore two copies of the mutation are needed for a horse to be affected. Horses homozygous for the mutation usually die or require euthanasia within 72 hours. FFS affects more than 20 breeds, such as Draft, Paint, and Quarter Horse, but the disease is most prevalent in the Warmblood population. The disease is incurable, but early detection by genetic testing can help identify FFS carriers and prevent further breeding by proper selection of mating pairs.
Results Reported As
Test Result |
Interpretation of test result |
CLEAR |
Tested mutation was not detected in animal with „clear“ result. Animal tested as clear has wild-type allele in homozygous state (i.e. two pairs of healthy alleles). It will not develop disease caused by tested mutation.* It will pass only wild-type allele to its offspring. |
CARRIER |
Tested mutation was detected in animal with „carrier“ result. Animal tested as carrier has one wild-type and one mutation allele, it is in heterozygous state. It will not develop disease caused by tested mutation.* It can pass wild-type or mutation allele to its offspring. |
AFFECTED |
Tested mutation was detected in animal with „affected“ result. Animal tested as affected has two copies of mutation alleles affecting the gene. It is likely the animal will experience a genetic disorder due to this mutation.** It will pass only mutation allele to its offspring. |
*Test excludes only tested mutation but not possible unknown mutations or factors that can lead to similar condition/symptoms.
** Potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Martin, K., Brooks, S., Vierra, M., Lafayette, W. T., McClure, S., Carpenter, M., & Lafayette, C. (2020). Fragile Foal Syndrome ( PLOD1 c.2032G>A) occurs across diverse horse populations. Animal Genetics, 52(1), 137–138. doi:10.1111/age.13020
Monthoux, C., de Brot, S., Jackson, M., Bleul, U., & Walter, J. (2015). Skin malformations in a neonatal foal tested homozygous positive for Warmblood Fragile Foal Syndrome. BMC Veterinary Research, 11(1), 12. doi:10.1186/s12917-015-0318-8
Reiter, S., Wallner, B., Brem, G., Haring, E., Hoelzle, L., Stefaniuk-Szmukier, M., … Bellone, R. R. (2020). Distribution of the Warmblood Fragile Foal Syndrome Type 1 Mutation (PLOD1 c.2032G>A) in Different Horse Breeds from Europe and the United States. Genes, 11(12), 1518. doi:10.3390/genes11121518