| Contents |
|---|
| Lavender Foal Syndrome (LFS) |
| Summary |
| Understanding the Results |
| Disease Name and Genes |
| Inheritance |
| Citations |
Lavender Foal Syndrome (LFS)
Summary
Lavender Foal Syndrome (LFS) is an inherited condition that causes seizures and the death of foals soon after birth. Symptoms include opisthotonus (a spasm of the muscles causing backward arching of the head, neck and spine) and stiff or paddling leg movements. These foals are unable to stand and nurse and are typically euthanized. There is no effective treatment.
Affected foals have a diluted coat color referred to as "lavender."
Date of Last Update: 08/02/2016
Results
Understanding the Results
Results of the genetic test for LFS are presented as shown below.
| Lavender Foal Syndrome (LFS) | ||
|---|---|---|
| N/N | Clear | This horse tested negative for Lf. |
| N/Lf | Carrier | Both the normal and mutant alleles are present. This horse is positive for the Lf mutation but will not develop symptoms. |
| Lf/Lf | Affected | This horse carries two copies of the Lf mutation and will die of the disease. |
Disease Name and Genes
Lavender Foal Syndrome (LFS) results from a frameshift mutation in the myosin Va (MYO5A) gene. A single-base deletion in exon 30 changes the reading frame and results in a premature stop codon.
Inheritance
Lavender Foal Syndrome (LFS) is caused by a recessive variant of the MYO5A gene. The recessive allele is commonly abbreviated as Lf, with the dominant wild-type allele abbreviated as N.
Carriers of the recessive allele (N/Lf) have no symptoms of the disease. If two carriers are bred, each foal has a 25% chance of having two copies of the normal allele (N/N), a 50% chance of being a carrier (N/Lf), and a 25% chance of being affected (Lf/Lf).
If a carrier of the recessive allele (N/Lf) is bred to a normal horse (N/N), each foal has a 50% chance of having two copies of the normal allele (N/N) and a 50% chance of being a carrier (N/Lf).
