OMIA 001000-9796 : Thrombasthenia in Equus caballus

In other species: dog , domestic cat

Possibly relevant human trait(s) and/or gene(s)s (MIM numbers): 273800 (trait) , 607759 (gene)

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal Recessive

Considered a defect: yes

Key variant known: yes

Year key variant first reported: 2006

Cross-species summary: More specifically called Glanzmann thrombasthenia.

Molecular basis: Christopherson et al. (2006) reported a "single guanine to cytosine (CGG to CCG) substitution in codon 41 in exon 2" of ITGA2B that "would result in the substitution of a proline for an arginine in a highly conserved region of the encoded protein" as a likely causal variant in an affected Thoroughbred cross and in an affected Quarter Horse. Noting that the affected Quarter Horse was only heterozygous for this variant, Christopherson et al. (2006) hypothesised that this horse " is likely a compound heterozygote" for this variant and a second yet-to-be-discovered variant.

Christopherson et al. (2007) reported that the second variant in the affected Quarter Horse described in 2006 is "a 10-bp deletion including the splice site between exon 11 and intron 11 . . . [that] would be predicted to result in a lack of splicing of intron 11 and inclusion of a premature stop codon 50 bp downstream of the mutation in the incompletely spliced mRNA."

Sanz et al. (2011) reported the same 10-bp deletion as being likely causative in a Peruvian Paso mare.

Macieira et al. (2011) reported "A point mutation from G to C in exon 2 of ITGA2B causing a substitution of the expected amino acid arginine 72 (Arg(72)) by a proline (Pro(72))" as the likely causal variant for an affected Oldenburg filly, stating that this variant "corresponds" to the variant reported by Christopherson et al. (2006).

Prevalence: Leite et al. (2020) reported that the two known likely causal variants were completely absent from 1053 DNA samples of clinically healthy Quarter Horse (n = 679) and Warmblood horses (n = 374) in Brazil, consistent with the observation that "this disease has not been described in Brazil". Although their samples were of adequate size, the authors rightly concluded that "it is not possible to affirm that there are no horses carrying mutated alleles in Brazil."

Breeds: Oldenburger, Quarter Horse, Thoroughbred.

Associated gene:

Symbol Description Species Chr Location OMIA gene details page Other Links
ITGA2B integrin alpha 2b Equus caballus 11 NC_009154.3 (19241506..19257092) ITGA2B Homologene, Ensembl, NCBI gene


By default, variants are sorted chronologically by year of publication, to provide a historical perspective. Readers can re-sort on any column by clicking on the column header. Click it again to sort in a descending order. To create a multiple-field sort, hold down Shift while clicking on the second, third etc relevant column headers.

WARNING! Inclusion of a variant in this table does not automatically mean that it should be used for DNA testing. Anyone contemplating the use of any of these variants for DNA testing should examine critically the relevant evidence (especially in breeds other than the breed in which the variant was first described). If it is decided to proceed, the location and orientation of the variant sequence should be checked very carefully.

Since October 2021, OMIA includes a semiautomated lift-over pipeline to facilitate updates of genomic positions to a recent reference genome position. These changes to genomic positions are not always reflected in the ‘acknowledgements’ or ‘verbal description’ fields in this table.

OMIA Variant ID Breed(s) Variant Phenotype Gene Allele Type of Variant Source of Genetic Variant Reference Sequence Chr. g. or m. c. or n. p. Verbal Description EVA ID Inferred EVA rsID Year Published PubMed ID(s) Acknowledgements
164 Quarter Horse Thoroughbred Thrombasthenia ITGA2B missense Naturally occurring variant EquCab3.0 11 g.19245752G>C c.215G>C p.(R72P) NM_001081793.1; NP_001075262.1; originally published as p.(R41P) and listed by Leite et al. (2019) as c.122G>C; coordinates in this table have been updated to a recent reference genome and / or transcript 2006 16407493
512 Peruvian Paso Quarter Horse Thrombasthenia ITGA2B deletion, small (<=20) Naturally occurring variant EquCab3.0 11 g.19247983_19247992del g.19247983_19247992delCAGGTGAGGA 2007 17338169 g. coordinates obtained from Dahlgren et al. (2020)


Note: the references are listed in reverse chronological order (from the most recent year to the earliest year), and alphabetically by first author within a year.
2020 Dahlgren, A.R., Tablin, F., Finno, C.J. :
Genetics of equine bleeding disorders. Equine Vet J :, 2020. Pubmed reference: 32463964. DOI: 10.1111/evj.13290.
2019 Leite, R.O., Ferreira, J.F., Araújo, C.E.T., Delfiol, D.J.Z., Takahira, R.K., Borges, A.S., Oliveira-Filho, J.P. :
Prevalence of the Mutations Responsible for Glanzmann Thrombasthenia in Horses in Brazil. Animals (Basel) 9:, 2019. Pubmed reference: 31766112. DOI: 10.3390/ani9110960.
2011 Macieira, S., Lussier, J., Bédard, C. :
Characterization of the cDNA and genomic DNA sequence encoding for the platelet integrin alpha IIB and beta III in a horse with Glanzmann thrombasthenia. Can J Vet Res 75:222-7, 2011. Pubmed reference: 22210999.
Sanz, MG., Wills, TB., Christopherson, P., Hines, MT. :
Glanzmann thrombasthenia in a 17-year-old Peruvian Paso mare. Vet Clin Pathol 40:48-51, 2011. Pubmed reference: 21291483. DOI: 10.1111/j.1939-165X.2011.00289.x.
2007 Christopherson, PW., van Santen, VL., Livesey, L., Boudreaux, MK. :
A 10-base-pair deletion in the gene encoding platelet glycoprotein IIb associated with Glanzmann thrombasthenia in a horse. J Vet Intern Med 21:196-8, 2007. Pubmed reference: 17338169.
Macieira, S., Rivard, G.E., Champagne, J., Lavoie, J.P., Bédard, C. :
Glanzmann thrombasthenia in an Oldenbourg filly. Vet Clin Pathol 36:204-8, 2007. Pubmed reference: 17523098.
2006 Christopherson, PW., Insalaco, TA., van Santen, VL., Livesey, L., Bourne, C., Boudreaux, MK. :
Characterization of the cDNA Encoding alphaIIb and beta3 in normal horses and two horses with Glanzmann thrombasthenia. Vet Pathol 43:78-82, 2006. Pubmed reference: 16407493. DOI: 10.1354/vp.43-1-78.
2005 Livesey, L., Christopherson, P., Hammond, A., Perkins, J., Toivio-Kinnucan, M., Insalaco, T., Boudreaux, MK. :
Platelet dysfunction (Glanzmann's thrombasthenia) in horses. J Vet Intern Med 19:917-9, 2005. Pubmed reference: 16355691.

Edit History

  • Created by Frank Nicholas on 03 Nov 2010
  • Changed by Frank Nicholas on 11 Sep 2011
  • Changed by Frank Nicholas on 09 Dec 2011
  • Changed by Frank Nicholas on 05 Dec 2012
  • Changed by Frank Nicholas on 30 Jan 2020
  • Changed by Frank Nicholas on 03 Feb 2020
  • Changed by Frank Nicholas on 02 Jun 2020