LFS is a fatal neurological disorder
Lavender Foal Syndrome
Breeds known to be affected
Arabian and related breeds
LFS causes neurological dysfunction in foals. The symptoms include seizures, hyperextension of the limbs, neck and back, leg paddling, and inability to stand. As the name suggests, LFS also dilutes to the coat to a pale lavender pink or silver colour. The foal will not improve and will either die or should be euthanised.
LFS is a recessive disorder so two copies of the defective version of the MYO5A gene must be inherited (LFS/LFS) for a foal to be affected. If a horse is a carrier (n/LFS), it will not show any clinical signs of LFS. However, there is a 50% chance it will pass the variant to its offspring, so mating to other carriers should be avoided to prevent the birth of an affected foal. LFS is caused by a mutation in the MYO5A gene and is more frequently observed in (although is not limited to) Arabian horses with Egyptian heritage.
Interpretation of results
n/n: Horse does not carry the mutation associated with LFS.
n/LFS: Horse has one copy of the mutation associated with LFS.
LFS/LFS: Horse has two copies of the mutation associated with LFS.
Bierman et al. Lavender foal syndrome in Arabian horses is caused by a single-base deletion in the MYO5A gene. Animal Genetics 2010;41(Suppl 2):199-201 doi:10.1111/j.1365-2052.2010.02086.x
Brooks et al. Whole-genome SNP association in the horse: Identification of a deletion in myosin Va responsible for Lavender Foal Syndrome. PLoS Genet 6: e1000909 doi:10.1371/journal.pgen.1000909