OMIA:002692-9796 : Night blindness, congenital stationary, GRM6-related in Equus caballus (horse)
Links to MONDO diseases:
Mendelian trait/disorder: yes
Considered a defect: yes
Key variant known: yes
Species-specific symbol: CSNB2
Species-specific description: Hack et al. (2021) reported a Tennessee Walking Horse with congenital stationary night blindness (CSNB) that did not have a the TRPM1 variant known to cause CSNB in horses (see OMIA:001341-9796 : Night blindness, congenital stationary, TRPM1-related in Equus caballus).
Esdaile et al. (2023) "provides additional evidence that GRM6 c.533C>T homozygosity is likely causal to CSNB in Tennessee Walking Horses, Standardbreds, and Missouri Fox Trotting Horses."
Molecular basis: Hack et al. (2021): "WGS [whole genome sequencing] analysis identified a missense mutation in metabotropic glutamate receptor 6 (GRM6) (c.533C>T p.Thr178Met)."
Prevalence: Hack et al. (2021): "This variant [GRM6 c.533C>T] was not detected in 273 horses from three additional breeds. The estimated allele frequency in Tennessee Walking Horses is 10%."
Esdaile et al. (2023) "The CSNB2 allele was present in nine breeds [American Quarter Horse, Racking Horse, Rocky Mountain Horse, American Saddlebred, Spotted Saddle Horse, Standardbred (pacer), Miniature Horse, Missouri Fox Trotting Horse, Morgan], ranging in frequency from 0.0010 in American Quarter Horses (n = 486) to 0.17 in pacing Standardbreds (n = 110 ...). The CSNB2 allele was not detected in trotting Standardbreds (n = 70), Thoroughbreds (n = 1787), Hackney Horses (n = 47), Hackney Ponies (n = 44), and Shetland Ponies (n = 99 ...).
American Saddle Horse (Horse) (VBO_0000898),
American Trotter (Horse) (VBO_0000899),
Miniature Horse (Horse) (VBO_0016848),
Missouri Fox Trotting Horse, United States of America (Horse) (VBO_0011833),
Morgan (Horse) (VBO_0001022),
Quarter Horse (Horse) (VBO_0001057),
Rocky Mountain, United States of America (Horse) (VBO_0011836),
Spotted Saddle Horse,
Tennessee Walking Horse (Horse) (VBO_0001081).
Breeds in which the phene has been documented. For breeds in which a likely causal variant has been documented, see the variant table below
|Symbol||Description||Species||Chr||Location||OMIA gene details page||Other Links|
|GRM6||glutamate receptor, metabotropic 6||Equus caballus||14||NC_009157.3 (2652585..2667335)||GRM6||Homologene, Ensembl , NCBI gene|
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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|
|1552||American Saddle Horse (Horse) American Trotter (Horse) Miniature Horse (Horse) Missouri Fox Trotting Horse, United States of America (Horse) Morgan (Horse) Quarter Horse (Horse) Racking horse Rocky Mountain, United States of America (Horse) Spotted Saddle Horse Tennessee Walking Horse (Horse)||Night blindness, congenital stationary, GRM6-related||GRM6||missense||Naturally occurring variant||EquCab3||14||g.2655618C>T||c.533C>T||p.(T178M)||XM_001916934.4; XP_001916969.3; variant initially reported in Tennessee Walking horse and later reported in other breeds [PMID:37815029]||rs1138010744||2021||32654228|
Cite this entry
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.
|2023||Esdaile, E., Knickelbein, K.E., Donnelly, C.G., Ferneding, M., Motta, M.J., Story, B.D., Avila, F., Finno, C.J., Gilger, B.C., Sandmeyer, L., Thomasy, S., Bellone, R.R. :|
|Additional evidence supports GRM6 p.Thr178Met as a cause of congenital stationary night blindness in three horse breeds. Vet Ophthalmol :, 2023. Pubmed reference: 37815029 . DOI: 10.1111/vop.13151.|
|2021||Hack, Y.L., Crabtree, E.E., Avila, F., Sutton, R.B., Grahn, R., Oh, A., Gilger, B., Bellone, R.R. :|
|Whole-genome sequencing identifies missense mutation in GRM6 as the likely cause of congenital stationary night blindness in a Tennessee Walking Horse. Equine Vet J 53:316-323, 2021. Pubmed reference: 32654228 . DOI: 10.1111/evj.13318.|
- Created by Imke Tammen2 on 10 May 2023
- Changed by Imke Tammen2 on 10 May 2023
- Changed by Imke Tammen2 on 15 Oct 2023