Categories: Vision / eye phene

Mendelian trait/disorder: unknown

Disease-related: yes

Species-specific name: Also known as Ophthalmia.

Inheritance: The MHC associations reported by Deeg et al. (2004) and Kaese et al. (2005) implied a non-zero heritability for this disease.

Mapping: In a GWAS on 79 affected and 65 control German warmblood horses, each genotyped with the Illumina equine SNP50 bead chip (yielding 37,040 informative SNPs), Kulbrock et al. (2013) revealed a large-effect QTL at 49.3Mb on chromosome ECA20, very near to two interleukin genes, namely IL-17A and IL-17F, and provided some support for the previously published MHC associations (the MHC being also on ECA20, at around 32Mb). Hack et al. (2022) "investigate potential genetic risk factors for ERU in the Icelandic horse. Fifty-six Icelandic horses (11 affected with ERU and 45 controls) ... were included in the study. A case-control GWAS was performed using the GGP Equine 80K array on the Illumina Infinium HD Beadchip using 40 horses. A mixed linear model analysis identified a single SNP on ECA 11 (BIEC2_141650; NC_009154.3:g.3817009A>G) that reached genome-wide significance (p = 1.79 × 10-7 ). This variant was within an intron of tissue inhibitor of metalloproteinase 2 (TIMP2), a gene previously implicated in ERU. Sanger sequencing identified a single coding variant in this gene; however it was a synonymous mutation (NC_009154.3:g.3858193C>T) and was not perfectly concordant with ERU phenotype (p = 0.68). Further investigation of TIMP2 is warranted."

Breeds: Appaloosa (Horse) (VBO_0000904), Icelandic Horse (Horse) (VBO_0000991), Knabstrupper (Horse) (VBO_0001008), Warmblood (Horse) (VBO_0017483).
Breeds in which the phene has been documented. (If a likely causal variant has been documented for the phene, see the variant table breeds in which the variant has been reported).