The Veterinary record2011; 169(25); 655; doi: 10.1136/vr.100235

Population screening of endangered horse breeds for the foal immunodeficiency syndrome mutation.

Abstract: The Fell and Dales are UK pony breeds that have small populations and may be at risk from in-breeding and inherited diseases. Foal immunodeficiency syndrome (FIS) is a lethal inherited disease caused by the recessive mutation of a single gene, which affects both Fell and Dales ponies and potentially other breeds that have interbred with either of these. FIS, previously known as Fell pony syndrome, is characterised by progressive anaemia and severe B lymphocyte deficiency. The identification of the causal mutation for this disease led to the recent development of a DNA-based carrier test. In this study, the authors used this test to estimate the prevalence of the FIS mutation in the Fell and Dales populations, revealing that approximately 18 per cent of adult Dales ponies and 38 per cent of adult Fell ponies are carriers of the FIS defect. In addition, a study of five potential at-risk breeds was conducted to assess the transfer of the FIS defect into these populations. Of the 192 coloured ponies tested, two were confirmed as FIS carriers: No carriers were found among 210 Clydesdales, 208 Exmoor ponies, 161 Welsh section D, 49 part-bred Welsh section D and 183 Highland ponies.
Publication Date: 2011-10-20 PubMed ID: 22016514DOI: 10.1136/vr.100235Google Scholar: Lookup
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  • Journal Article
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This research study investigates the prevalent mutation for Foal Immunodeficiency Syndrome (FIS) in two endangered horse breeds, Fell and Dales, in the UK through a DNA-based test. The saga expands to five other at-risk breeds for evaluating the possible transmission of the mutation. Peculiarly, 18 percent of Dales and 38 percent of Fell were FIS carriers, whereas two from 192 colored breeds exhibited the defects, and none among other mentioned breeds.

Population Screening

  • The researchers used a DNA-based carrier test, which was developed following the identification of the FIS mutation in specific horse breeds.
  • The focus was on two endangered pony breeds in the UK – Fell and Dales. The study aimed to estimate the prevalence of the FIS mutation in these breeds.
  • The findings showed around 18% Dales and 38% Fell adult ponies carried the FIS gene mutation. It signifies that a considerable population of these breeds is at risk of developing this lethal inherited disease.

Foal Immunodeficiency Syndrome (FIS)

  • FIS is marked by progressive anaemia and severe B lymphocyte deficiency. It is caused by the recessive mutation of a single gene, which exists in both Fell and Dales ponies and other breeds that have interbred with either.
  • Although lethal, the early identification of this mutation via a DNA-based carrier test enables breeders to make informed breeding decisions and possibly prevent the disease’s spread.

Screening of Additional At-risk Breeds

  • The research also delved into five other at-risk breeds, presuming that the FIS mutation might have penetrated these populations due to interbreeding.
  • The analyzed breeds were: Clydesdales, Exmoor ponies, Welsh section D, part-bred Welsh section D, and Highland ponies.
  • From a total of 192 colored ponies investigated, only two were confirmed FIS carriers. Astonishingly, none of the ponies from the other breeds manifested as carriers of the FIS mutation.

The study accentuates the necessity of frequent genetic testing for inherited diseases in breeds with small populations or a history of inbreeding, to safeguard their health and preserve diversity.

Cite This Article

Fox-Clipsham LY, Brown EE, Carter SD, Swinburne JE. (2011). Population screening of endangered horse breeds for the foal immunodeficiency syndrome mutation. Vet Rec, 169(25), 655.


ISSN: 2042-7670
NlmUniqueID: 0031164
Country: England
Language: English
Volume: 169
Issue: 25
Pages: 655

Researcher Affiliations

Fox-Clipsham, L Y
  • Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, CB8 7UU, UK.
Brown, E E
    Carter, S D
      Swinburne, J E

        MeSH Terms

        • Animals
        • Carrier State / veterinary
        • Female
        • Genetic Testing / veterinary
        • Horse Diseases / diagnosis
        • Horse Diseases / genetics
        • Horses
        • Immunologic Deficiency Syndromes / diagnosis
        • Immunologic Deficiency Syndromes / genetics
        • Immunologic Deficiency Syndromes / veterinary
        • Inbreeding
        • Male
        • Mutation


        This article has been cited 1 times.
        1. Dell A, Curry M, Yarnell K, Starbuck G, Wilson PB. Genetic analysis of the endangered Cleveland Bay horse: A century of breeding characterised by pedigree and microsatellite data.. PLoS One 2020;15(10):e0240410.
          doi: 10.1371/journal.pone.0240410pubmed: 33119607google scholar: lookup