Foal Immunodeficiency Syndrome

Foal Immunodeficiency syndrome (FIS) or Fell Pony Syndrome affects two UK breeds of ponies, Fell and Dales. FIS is a recessive genetic disease that affects 10% of foals each year.[1] This genetic disease starts to show symptoms 2–3 weeks after the foal is born. The foal begins to show weakness, have a dull coat, and anorexia.[1] By the age of 3 months, the foal typically dies giving this disease a 100% mortality rate.[2]

Symptoms

The first symptoms of FIS are diarrhea, nasal discharge, poor growth, pale gums, and decrease of appetite. Their vision may begin to decrease due to bacterial infections.[1] These continue to worsen until the malnourishment completely kills them.

Genetics

The gene responsible for the disease is the sodium/myo-inositol cotransporter gene (SLC5A3). A single mutation in the gene causes the expression of FIS in the foal.[1] In a normal SLC5A3 gene, it codes for a protein that prevents the accumulation of myo-inositol in high concentrations that would otherwise hinder cell functions.[3] It is also a regulatory response in tissues such as lymphoid tissue. Since FIS is a recessive genetic disease, the foal must have both heterozygous parents for the allele also known as carriers. Although this disease affects two UK breeds, the mutation is also found in 9% of US and European Gypsy horses.[1]

Diagnosis

Any Fell, Dales, or Gypsy Ponies can be tested for FIS along with any other ponies that have these ponies’ blood-lines. A simple DNA test will show whether or not the pony has the mutation for FIS, is a carrier, or neither. The results will look like FIS/FIS, FIS/n, or n/n where the n stands no mutation.[1] The cost to submit a sample is cost effective and should be done.

Treatment

There is no treatment yet which is why it always leads to death.[2]

Outlook

With the help of recently having the horse genome sequenced, it has allowed for the DNA test for FIS to be created. Over time this test should help breeders and owners become more aware of which ponies should breed together and lower the allele frequency of FIS.[2]

References

  1. 1 2 3 4 5 6 Foal Immunodeficiency Syndrome (FIS). (n.d.). Retrieved September 06, 2016, from http://www.animalgenetics.us/Equine/Genetic_Disease/FIS.asp
  2. 1 2 3 Fox-Clipsham, L. Y., Carter, S. D., Goodhead, I., Hall, N., Knottenbelt, D. C., May, P. D. F., … Swinburne, J. E. (2011). Identification of a Mutation Associated with Fatal Foal Immunodeficiency Syndrome in the Fell and Dales Pony. PLoS Genetics, 7(7), e1002133. doi:10.1371/journal.pgen.1002133
  3. ↑ SLC5A3 Gene. (n.d.). Retrieved September 06, 2016, from http://www.genecards.org/cgi-bin/carddisp.pl?gene=SLC5A3
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