{"topic_id":"companion_breed_health_miniature_horse_horse_omia5331_horse","category":"companion-breed-health","context":"---\nlicense: permission_granted\ntopic_id: companion_breed_health_miniature_horse_horse_omia5331_horse\ncategory: companion-breed-health\ntitle: \"Miniature Horse (Horse) — Night blindness, congenital stationary, GRM6-related (hereditary; OMIA-verified breed predisposition)\"\nlang: en\nsource: \"OMIA (Online Mendelian Inheritance in Animals, University of Sydney) breed-specific hereditary-disorder record, saved verbatim to source_file; C1 substring-verified. Pulled 2026-08-23 from local OMIA database dump.\"\nsource_file: pdf-raw/breed-health/miniature_horse_horse_omia5331_5331.txt\ndate_parsed: 2026-08-23\ntokens_estimated: 348\nverification:\n  method: substring_match\n  claims: 5\n  passed: 5\n  date: 2026-08-23\nrecovered: false\npath: companion-breed-health/companion_breed_health_miniature_horse_horse_omia5331_horse/01_companion_breed_health_miniature_horse_horse_omia5331_horse.md\nsource_document: \"OMIA — Online Mendelian Inheritance in Animals (University of Sydney)\"\ncitation:\n  authority: \"OMIA — Online Mendelian Inheritance in Animals (University of Sydney)\"\n  title: \"Miniature Horse (Horse) — Night blindness, congenital stationary, GRM6-related (hereditary; OMIA-verified breed predisposition)\"\n  url: \"https://omia.org/OMIA002692/9796/\"\n  retrieved: \"2026-08-23\"\n  ref: \"OMIA breed-specific hereditary-disorder records (omia.org), derived from local OMIA database dump; dataset: https://doi.org/10.25910/2AMR-PV70\"\n  doc_type: \"academic animal-genetics database (breed-specific disorder entries)\"\n  needs_review: false\n\nverification_derived:\n  method: derived_from_dataset\n  source: \"OMIA database dump (omia.xml, local); fields Gene/Variant/Article/OMIM\"\n  note: \"Structured fields (gene, variant rsID/protein change, PubMed/DOI references, OMIM cross-link) extracted from OMIA dump and presented with first-hand values; not verbatim prose.\"---\n\n# Miniature Horse (Horse) — Night blindness, congenital stationary, GRM6-related (hereditary; OMIA-verified breed predisposition)\n\nSource: first-hand OMIA (University of Sydney) breed-specific hereditary-disorder record, saved verbatim to `source_file`; every claim below is a C1 byte-substring of it.\n\n## Claims\n\n- `Breed: Miniature Horse (Horse)`\n- `Disorder: `\n- `Summary: 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. (2024) provides additional evidence that GRM6 c.533Cgt;T homozygosity is likely causal to CSNB in Tennessee Walking Horses, Standardbreds, and Missouri Fox Trotting Horses.`\n- `Defect: yes`\n- `Prevalence: Hack et al. (2021): This variant [GRM6 c.533Cgt;T] was not detected in 273 horses from three additional breeds. The estimated allele frequency in Tennessee Walking Horses is 10%. Esdaile et al. (2024): 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 ...).`\n## Associated gene(s)\nDerived from OMIA database dump (omia.xml, local); structured field, not verbatim prose. First-hand values below are verbatim substrings of the topic's pdf-raw/omia/<phene_id>.txt source file.\n- Gene: Entrez Gene ID 388955788 (no symbol in OMIA GeneSynonym) — OMIA Phene_Gene\n- OMIA molecular-genetics note: Hack et al. (2021): \"WGS [whole genome sequencing] analysis identified a missense mutation in metabotropic glutamate receptor 6 (GRM6) (c.533C&gt;T p.Thr178Met).\"\n\n## Evidence (references)\nDerived from OMIA database dump (omia.xml, local); structured field, not verbatim prose. First-hand values below are verbatim substrings of the topic's pdf-raw/omia/<phene_id>.txt source file.\n- 2021. 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 — PubMed:PMID32654228 | DOI:10.1111/evj.13318 — OMIA Phene_Article / Article\n- 2024. Additional evidence supports GRM6 p.Thr178Met as a cause of congenital stationary night blindness in three horse breeds. Vet Ophthalmol — PubMed:PMID37815029 | DOI:10.1111/vop.13151 — OMIA Phene_Article / Article\n- 2024. Consensus guidelines for nomenclature of companion animal inherited retinal disorders. Vet Ophthalmol — PubMed:PMID38334230 | DOI:10.1111/vop.13185 — OMIA Phene_Article / Article\n\n## Comparative medicine (human OMIM)\nDerived from OMIA database dump (omia.xml, local); structured field, not verbatim prose. First-hand values below are verbatim substrings of the topic's pdf-raw/omia/<phene_id>.txt source file.\n- OMIM:604096 (type: gene) — OMIA Group_OMIM (via OMIA_ID)\n- OMIM:257270 (type: trait) — OMIA Group_OMIM (via OMIA_ID)\n","sources":["companion-breed-health — Miniature Horse (Horse) — Night blindness, congenital stationary, GRM6-related (hereditary; OMIA-verified breed predisposition)"],"source":{"authority":"companion-breed-health","title":"Miniature Horse (Horse) — Night blindness, congenital stationary, GRM6-related (hereditary; OMIA-verified breed predisposition)","url":"https://pubmed.ncbi.nlm.nih.gov/32654228/","retrieved":"","ref":"PMID 32654228","doc_type":"official source","source_document":"","verification_file":""},"source_document":"","source_file":"","trust":{"authority_tier":"ungraded","fidelity":"verbatim","license":null,"display_grade":"pending"},"tokens_estimated":817,"generated_at":null,"tip":"Use /api/v1/topics to discover more topics. /api/v1/nutrient for precise single-point queries. /api/v1/cross_compare for 2-3 standard comparisons."}