Immunodeficiency syndrome, SLC5A3-related

Gene: SLC5A3

Transmission: Autosomal, recessive

For an autosomal recessive genetic disease an animal must have two copies of the mutation in question to be at risk of developing the disease.  Both parents of an affected animal must be carriers of at least one copy of the mutation.  Animals that have only one copy of the mutation are not at risk of developing the disease but are carrier animals that can pass the mutation on to future generations.

Mutation: Substitution, SLC5A3 gene; c.1352 C>T, p.(Pro451Leu), chromosome 26.

Breed: Dales Pony, Fell Pony

Medical system: Immune

Age of onset of symptoms: 4-6 weeks.

The Dales and Fell pony breeds are two related breeds of horses from Northern England.  A syndrome of immunodeficiency was diagnosed in Fell ponies in the late 1990s and in Dales ponies in the late 2000s.  Foals were born healthy but within a few weeks and coincident to declining maternal colostrum levels would show signs of diarrhea, weight loss, nasal discharge, coughing and pneumonia.  A progressive anemia with severe B lymphocyte deficiency and reduced antibody production was the cause of the clinical signs.  Affected animals would die after several months due to opportunistic infections.  DNA studies identified a mutation in the SLC5A3 gene, this gene codes for a sodium transporter protein important for immune system function.  The frequency of carrier animals in Fell pony population was initially found to be 40%, while in the Dales pony population it was 20%.  Subsequent use of DNA tests to identify carrier animals has markedly reduced the frequency of this disease.   Veterinarians and breeders of Dales and Fell ponies should still be aware of this disease.

References:

OMIA link: [1578-9796]

Carter SD, Fox-Clipsham LY, Christley R, Swinburne J. (2013) Foal immunodeficiency syndrome: carrier testing has markedly reduced disease incidence.  Vet Rec. 172(15):398 [pm/23486505]

Bailey E. (2011) Screening for foal immunodeficiency syndrome. Vet Rec 169:653-4. [pm/22184351]

Fox-Clipsham LY, Brown EE, Carter SD, Swinburne JE. (2011) Population screening of endangered horse breeds for the foal immunodeficiency syndrome mutation. Vet Rec 169:655. [pm/22016514]

Fox-Clipsham LY, Carter SD, Goodhead I, et al. (2011) Identification of a mutation associated with fatal foal immunodeficiency syndrome in the fell and dales pony. PLoS Genet 7:e1002133.  [pm/21750681]

Scholes SF, Holliman A, May PD, Holmes MA. (1998) A syndrome of anaemia, immunodeficiency and peripheral ganglionopathy in Fell pony foals. Vet Rec 142:128-34. [pm/9507645]

Contributed by: Marie-Lune Foczeny and Mélyna Bergeron, Class of 2029, Faculté de médecine vétérinaire, Université de Montréal.  (Translation DWS)