{"topic_id":"companion_breed_health_thoroughbred_horse_omia4757_horse","category":"companion-breed-health","context":"---\nlicense: permission_granted\ntopic_id: companion_breed_health_thoroughbred_horse_omia4757_horse\ncategory: companion-breed-health\ntitle: \"Thoroughbred (Horse) — Hypoparathyroidism, RAPGEF5-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/thoroughbred_horse_omia4757_4757.txt\ndate_parsed: 2026-08-23\ntokens_estimated: 332\nverification:\n  method: substring_match\n  claims: 7\n  passed: 7\n  date: 2026-08-23\nrecovered: false\npath: companion-breed-health/companion_breed_health_thoroughbred_horse_omia4757_horse/01_companion_breed_health_thoroughbred_horse_omia4757_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: \"Thoroughbred (Horse) — Hypoparathyroidism, RAPGEF5-related (hereditary; OMIA-verified breed predisposition)\"\n  url: \"https://omia.org/OMIA002458/9796/\"\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# Thoroughbred (Horse) — Hypoparathyroidism, RAPGEF5-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: Thoroughbred (Horse)`\n- `Disorder: `\n- `Mode of inheritance: Autosomal recessive`\n- `Clin feat: Beyer et al. (1997): “Five thoroughbred foals (4 fillies and 1 colt), all in good to excellent body condition, ranging in age from 4 days to 5 weeks at the time of onset of signs, were presented … . All 5 foals presented with tachycardia, hyperhidrosis, diarrhea or a recent history of diarrhea, and muscle rigidity or stiff gait. Four of the 5 foals presented for recumbency, seizure-like activity with opisthotonos, or pronounced extensor muscle rigidity. All 5 foals were hypocalcemic. All foals either died or had euthanasia performed.” The foals investigated by Rivas et al. (2020) presented with fatal idiopathic hypocalcemia, tetany and seizures.`\n- `Defect: yes`\n- `Pathology: In four of the 5 foals reported by Beyer et al. (1997) necropsy examination were conducted and in all 4 foals parathyroid tissue could not be identified. In the cases reported by Rivas et al. (2020) the only consistent gross or histologic lesions present across all cases was the absence of normal parathyroid glands.`\n- `Prevalence: Elcombe et al. (2023) reported the c.2624Cgt;A variant (OMIA variant 1369) at a frequency of less than 1% in the US Thoroughbred population (1988-2019).`\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 388955687 (no symbol in OMIA GeneSynonym) — OMIA Phene_Gene\n- OMIA molecular-genetics note: Rivas et al. (2020): \"We performed whole-genome sequencing of the two foals, their unaffected dams and four unaffected, unrelated TB horses. Both homozygosity mapping and an association analysis were used to prioritize potential genetic variants. Of the 2,808 variants that significantly associated with the phenotype using an AR mode of inheritance (P&lt;0.02) and located within a region of homozyg…\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- 2020. A nonsense variant in Rap Guanine Nucleotide Exchange Factor 5 (RAPGEF5) is associated with equine familial isolated hypoparathyroidism in Thoroughbred foals. PLoS Genet — PubMed:PMID32986719 | DOI:10.1371/journal.pgen.1009028 — OMIA Phene_Article / Article\n- 1997. Idiopathic hypocalcemia in foals. J Vet Intern Med — PubMed:PMID9470161 | DOI:10.1111/j.1939-1676.1997.tb00480.x — OMIA Phene_Article / Article\n- 2023. Prevalence of the RAPGEF5 c.2624C>A and PLOD1 c.2032G>A variants associated with equine familial isolated hypoparathyroidism and fragile foal syndrome in the US Thoroughbred population (1988-2019). Equine Vet J — PubMed:PMID36199159 | DOI:10.1111/evj.13883 — 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:609527 (type: gene) — OMIA Group_OMIM (via OMIA_ID)\n","sources":["companion-breed-health — Thoroughbred (Horse) — Hypoparathyroidism, RAPGEF5-related (hereditary; OMIA-verified breed predisposition)"],"source":{"authority":"companion-breed-health","title":"Thoroughbred (Horse) — Hypoparathyroidism, RAPGEF5-related (hereditary; OMIA-verified breed predisposition)","url":"https://pubmed.ncbi.nlm.nih.gov/32986719/","retrieved":"","ref":"PMID 32986719","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":856,"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."}