{"topic_id":"companion_breed_health_labrador_retriever_omia3969_dog","category":"companion-breed-health","context":"---\nlicense: permission_granted\ntopic_id: companion_breed_health_labrador_retriever_omia3969_dog\ncategory: companion-breed-health\ntitle: \"Labrador Retriever — Macular corneal dystrophy (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 2026-08-02 from local OMIA database dump.\"\nsource_file: pdf-raw/breed-health/labrador_retriever_omia3969_3969.txt\ndate_parsed: 2026-08-02\ntokens_estimated: 493\nverification:\n  method: substring_match\n  claims: 7\n  passed: 7\n  date: 2026-08-02\nrecovered: false\npath: companion-breed-health/companion_breed_health_labrador_retriever_omia3969_dog/01_companion_breed_health_labrador_retriever_omia3969_dog.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: \"Labrador Retriever — Macular corneal dystrophy (hereditary; OMIA-verified breed predisposition)\"\n  url: \"https://omia.org/OMIA002071/9615/\"\n  retrieved: \"2026-08-02\"\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\n\n# Labrador Retriever — Macular corneal dystrophy (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: Labrador Retriever (Dog)`\n- `Disorder: `\n- `Mode of inheritance: Autosomal recessive`\n- `Clin feat: Busse et al. (2019): Labrador Retrievers affected by MCD were presented between the age of 4.5 and 6 years of age with a history of cloudy eyes and/or visual impairment. Findings on ophthalmic examination included a diffuse haze of the corneal stroma and multiple, well-demarcated, off-white to yellow-brown, punctate corneal opacities heterogeneous in size. Corneal vascularization developed in most dogs as the disease progressed. Disease progression was associated with increased density of the corneal haze as well as increased number and size of the focal opacities and dogs developed significant visual impairment. Spectral domain-optical coherence tomography revealed multifocal hyper-reflective regions within the stroma. In vivo confocal microscopy revealed marked alterations in reflectivity throughout the entire stroma. Normal keratocytes could not be identified in affected areas.`\n- `Defect: yes`\n- `Pathology: Busse et al. (2019): Histopathology showed stromal collagen fibers separated by acidophilic granular material on hematoxylin and eosin stain. The material stained with periodic acid-Schiff and colloidal iron stain but not with Masson trichrome stain, confirming the accumulation of glycosaminoglycans. On electron microscopic ultrastructural examination, keratocytes presented with vacuolated rough endoplasmic reticulum and multiple electron dense cytoplasmic inclusions. In areas keratocytes appeared ruptured, with cell organelles and proteinaceous material grouped together between collagen fibers.`\n- `Prevalence: As reported by Tetas Pont et al. (2016), The mutant allele was present in the unrelated LR cohort [of 89 unrelated Labrador Retrievers with unknown clinical status] at a frequency of 0.017, suggesting carrier and affection rates of 3.3% and 0.028%, respectively.`\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: CHST6 (Entrez Gene ID 388254349) — OMIA Phene_Gene / GeneSynonym\n- OMIA molecular-genetics note: By sequencing the most likely comparative candidate gene (CHST6) in one affected and one normal Labrador Retriever, Tetas Pont et al. (2016) identified the likely causal mutation as c.814C&gt;A; p.R272S. Supporting evidence was provided by evidence that \"six LR affected with MCD were homozygous for the mutant allele, while 140/151 control LR were homozygous for the wild-type allele and 11/151 were…\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- 2016. A carbohydrate sulfotransferase-6 (CHST6) gene mutation is associated with macular corneal dystrophy in Labrador Retrievers. Vet Ophthalmol — PubMed:PMID26585178 | DOI:10.1111/vop.12332 — OMIA Phene_Article / Article\n- 2013. Case report: A form of macular corneal dystrophy in a Labrador retriever. Abstract presentation in European College of Veterinary Ophthalmologists — OMIA Phene_Article / Article\n- 2019. Phenotype of macular corneal dystrophy in Labrador Retrievers: A multicenter study. Vet Ophthalmol — PubMed:PMID30701649 | DOI:10.1111/vop.12596 — OMIA Phene_Article / Article\n- 2021. The Blue Book: Ocular disorders presumed to be inherited in purebred dogs. 13th Edition. https://ofa.org/wp-content/uploads/2022/10/ACVO-Blue-Book-2021.pdf — 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:217800 (type: trait) — OMIA Group_OMIM (via OMIA_ID)\n- OMIM:605294 (type: gene) — OMIA Group_OMIM (via OMIA_ID)\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","sources":["companion-breed-health — Labrador Retriever — Macular corneal dystrophy (hereditary; OMIA-verified breed predisposition)"],"source":{"authority":"companion-breed-health","title":"Labrador Retriever — Macular corneal dystrophy (hereditary; OMIA-verified breed predisposition)","url":"https://pubmed.ncbi.nlm.nih.gov/26585178/","retrieved":"","ref":"PMID 26585178","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":960,"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."}