{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,14]],"date-time":"2026-01-14T15:16:23Z","timestamp":1768403783484,"version":"3.49.0"},"reference-count":41,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2022,3,22]],"date-time":"2022-03-22T00:00:00Z","timestamp":1647907200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Texas A&amp;M Molecular Cytogenetics and Animal Genetics Laboratories","award":["na"],"award-info":[{"award-number":["na"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>We present cytogenetic and genotyping analysis of a Thoroughbred foal with congenital neurologic disorders and its phenotypically normal dam. We show that the foal has non-mosaic trisomy for chromosome 26 (ECA26) but normal 2n = 64 diploid number because two copies of ECA26 form a metacentric derivative chromosome der(26q;26q). The dam has normal 64,XX karyotype indicating that der(26q;26q) in the foal originates from errors in parental meiosis or post-fertilization events. Genotyping ECA26 microsatellites in the foal and its dam suggests that trisomy ECA26 is likely of maternal origin and that der(26q;26q) resulted from Robertsonian fusion. We demonstrate that conventional and molecular cytogenetic approaches can accurately identify aneuploidy with a derivative chromosome but determining the mechanism and parental origin of the rearrangement requires genotyping with chromosome-specific polymorphic markers. Most curiously, this is the second case of trisomy ECA26 with der(26q;26q) in the horse, whereas all other equine autosomal trisomies are \u2018traditional\u2019 with three separate chromosomes. We discuss possible ECA26 instability as a contributing factor for the aberration and likely ECA26-specific genetic effects on the clinical phenotype. Finally, because ECA26 shares evolutionary homology with human chromosome 21, which trisomy causes Down syndrome, cytogenetic, molecular, and phenotypic similarities between trisomies ECA26 and HSA21 are discussed.<\/jats:p>","DOI":"10.3390\/ani12070803","type":"journal-article","created":{"date-parts":[[2022,3,22]],"date-time":"2022-03-22T14:55:35Z","timestamp":1647960935000},"page":"803","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["The Second Case of Non-Mosaic Trisomy of Chromosome 26 with Homologous Fusion 26q;26q in the Horse"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9539-8290","authenticated-orcid":false,"given":"Sharmila","family":"Ghosh","sequence":"first","affiliation":[{"name":"Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9390-4153","authenticated-orcid":false,"given":"Josefina","family":"Kj\u00f6llerstr\u00f6m","sequence":"additional","affiliation":[{"name":"Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Laurie","family":"Metcalfe","sequence":"additional","affiliation":[{"name":"Rood & Riddle Equine Hospital, Lexington, KY 40580, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Stephen","family":"Reed","sequence":"additional","affiliation":[{"name":"Rood & Riddle Equine Hospital, Lexington, KY 40580, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7385-0618","authenticated-orcid":false,"given":"Rytis","family":"Juras","sequence":"additional","affiliation":[{"name":"Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2276-475X","authenticated-orcid":false,"given":"Terje","family":"Raudsepp","sequence":"additional","affiliation":[{"name":"Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,3,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1159\/000118739","article-title":"Equine clinical cytogenetics: The past and future","volume":"120","author":"Lear","year":"2008","journal-title":"Cytogenet. Genome Res."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Bugno-Poniewierska, M., and Raudsepp, T. (2021). Horse Clinical Cytogenetics: Recurrent Themes and Novel Findings. Animals, 11.","DOI":"10.3390\/ani11030831"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1146\/annurev-animal-021815-111239","article-title":"Chromosome Aberrations and Fertility Disorders in Domestic Animals","volume":"4","author":"Raudsepp","year":"2016","journal-title":"Annu. Rev. Anim. Biosci."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"41","DOI":"10.1111\/j.1365-2052.2010.02101.x","article-title":"Chowdhary. Molecular heterogeneity of XY sex reversal in horses","volume":"41","author":"Raudsepp","year":"2010","journal-title":"Anim. Genet."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2945","DOI":"10.1038\/s41467-018-05290-6","article-title":"Horse Y chromosome assembly displays unique evolutionary features and putative stallion fertility genes","volume":"9","author":"Janecka","year":"2018","journal-title":"Nat. Commun."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"13314","DOI":"10.1038\/s41598-020-69967-z","article-title":"Whole genome analysis reveals aneuploidies in early pregnancy loss in the horse","volume":"10","author":"Shilton","year":"2020","journal-title":"Sci. Rep."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"431","DOI":"10.1016\/j.jevs.2008.06.003","article-title":"Autosomic 27 Trisomy in a Standardbred Colt","volume":"28","author":"Brito","year":"2008","journal-title":"J. Equine Vet. Sci."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Hole\u010dkov\u00e1, B., Schwarzbacherov\u00e1, V., Gald\u00edkov\u00e1, M., Koleni\u010dov\u00e1, S., Halu\u0161kov\u00e1, J., Stani\u010dov\u00e1, J., Verebov\u00e1, V., and Jutkov\u00e1, A. (2021). Chromosomal Aberrations in Cattle. Genes, 12.","DOI":"10.3390\/genes12091330"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Iannuzzi, A., Parma, P., and Iannuzzi, L. (2021). Chromosome Abnormalities and Fertility in Domestic Bovids: A Review. Animals, 11.","DOI":"10.3390\/ani11030802"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Donaldson, B., Villagomez, D.A.F., and King, W.A. (2021). Classical, Molecular, and Genomic Cytogenetics of the Pig, a Clinical Perspective. Animals, 11.","DOI":"10.3390\/ani11051257"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Szczerbal, I., and Switonski, M. (2021). Clinical Cytogenetics of the Dog: A Review. Animals, 11.","DOI":"10.3390\/ani11040947"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"176","DOI":"10.1002\/pd.4986","article-title":"A copy number variation genotyping method for aneuploidy detection in spontaneous abortion specimens","volume":"37","author":"Chen","year":"2017","journal-title":"Prenat. Diagn."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"280","DOI":"10.1038\/35066065","article-title":"To err (meiotically) is human: The genesis of human aneuploidy","volume":"2","author":"Hassold","year":"2001","journal-title":"Nat. Rev. Genet."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1016\/j.ajhg.2020.11.010","article-title":"Failure to recombine is a common feature of human oogenesis","volume":"108","author":"Hassold","year":"2021","journal-title":"Am. J. Hum. Genet."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"786","DOI":"10.1002\/ccr3.341","article-title":"Are de novo rea(21;21) chromosomes really de novo?","volume":"3","author":"Quibel","year":"2015","journal-title":"Clin. Case Rep."},{"key":"ref_16","first-page":"968","article-title":"Analysis of DNA polymorphisms suggests that most de novo dup(21q) chromosomes in patients with Down syndrome are isochromosomes and not translocations","volume":"47","author":"Antonarakis","year":"1990","journal-title":"Am. J. Hum. Genet."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"159","DOI":"10.1002\/ajmg.a.10113","article-title":"Mosaicism in a patient with Down syndrome reveals post-fertilization formation of a Robertsonian translocation and isochromosome","volume":"116","author":"Bandyopadhyay","year":"2003","journal-title":"Am. J. Med. Genet. A"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"297","DOI":"10.1146\/annurev.genet.34.1.297","article-title":"Molecular mechanisms for constitutional chromosomal rearrangements in humans","volume":"34","author":"Shaffer","year":"2000","journal-title":"Annu. Rev. Genet."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"92","DOI":"10.3126\/jnps.v37i1.16184","article-title":"De Novo Robertsonian Translocation t(21; 21) in a Child with Down Syndrome","volume":"37","author":"Israni","year":"2017","journal-title":"J. Nepal Paediatr. Soc."},{"key":"ref_20","first-page":"149","article-title":"An update of chromosomal abnormalities in mares","volume":"35","author":"Bowling","year":"1987","journal-title":"J. Reprod. Fertil. Suppl."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"679","DOI":"10.1139\/g90-101","article-title":"Two autosomal trisomies in the horse: 64,XX, \u221226, +t(26q26q) and 65,XX, +30","volume":"33","author":"Bowling","year":"1990","journal-title":"Genome"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"31","DOI":"10.1007\/978-1-59745-581-7_3","article-title":"FISH for mapping single copy genes","volume":"422","author":"Raudsepp","year":"2008","journal-title":"Methods Mol. Biol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"971","DOI":"10.1016\/S0140-6736(71)90287-X","article-title":"A rapid banding technique for human chromosomes","volume":"2","author":"Seabright","year":"1971","journal-title":"Lancet"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"433","DOI":"10.1023\/A:1018408811881","article-title":"International system for cytogenetic nomenclature of the domestic horse. Report of the Third International Committee for the Standardization of the domestic horse karyotype, Davis, CA, USA, 1996","volume":"5","author":"Bowling","year":"1997","journal-title":"Chromosome Res."},{"key":"ref_25","unstructured":"McGowan-Jordan, J., Simons, A., and Schmid, M. (2020). An International System for Human Cytogenomic Nomenclature, S. Karger."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"28","DOI":"10.1159\/000151313","article-title":"A 4103 marker integrated physical and comparative map of the horse genome","volume":"122","author":"Raudsepp","year":"2008","journal-title":"Cytogenet. Genome Res."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"688","DOI":"10.1159\/000512206","article-title":"Two Novel Cases of Autosomal Translocations in the Horse: Warmblood Family Segregating t(4;30) and a Cloned Arabian with a de novo t(12;25)","volume":"160","author":"Ghosh","year":"2020","journal-title":"Cytogenet. Genome Res."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"386","DOI":"10.1093\/jhered\/est003","article-title":"Microsatellite analysis of genetic diversity and population structure of Arabian horse populations","volume":"104","author":"Khanshour","year":"2013","journal-title":"J. Hered."},{"key":"ref_29","first-page":"180","article-title":"Genetic analysis of three Lithuanian native horse breeds","volume":"53","author":"Juras","year":"2003","journal-title":"Acta Agric. Scand. Sect. A Anim. Sci."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"233","DOI":"10.1038\/72708","article-title":"An economic method for the fluorescent labeling of PCR fragments","volume":"18","author":"Schuelke","year":"2000","journal-title":"Nat. Biotechnol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"487","DOI":"10.1111\/j.1365-2052.2004.01208.x","article-title":"Isolation, characterization and chromosome assignment of 341 newly isolated equine TKY microsatellite markers","volume":"35","author":"Tozaki","year":"2004","journal-title":"Anim. Genet."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"375","DOI":"10.1007\/BF00201838","article-title":"A molecular genetic approach to the identification of isochromosomes of chromosome 21","volume":"86","author":"Shaffer","year":"1991","journal-title":"Hum. Genet."},{"key":"ref_33","unstructured":"Rosenberg, R.N., and Pascual, J.M. (2015). Chapter 1\u2014Mendelian, Non-Mendelian, Multigenic Inheritance, and Epigenetics. Rosenberg\u2019s Molecular and Genetic Basis of Neurological and Psychiatric Disease, Academic Press. [5th ed.]."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1007\/s10577-007-1201-7","article-title":"Multidirectional cross-species painting illuminates the history of karyotypic evolution in Perissodactyla","volume":"16","author":"Trifonov","year":"2008","journal-title":"Chromosome Res."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1218","DOI":"10.1002\/ajmg.1320470818","article-title":"Further characterization of 19 cases of rea(21q21q) and delineation as isochromosomes or Robertsonian translocations in Down syndrome","volume":"47","author":"Shaffer","year":"1993","journal-title":"Am. J. Med. Genet."},{"key":"ref_36","first-page":"968","article-title":"Molecular characterization of de novo secondary trisomy 13","volume":"55","author":"Shaffer","year":"1994","journal-title":"Am. J. Hum. Genet."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"197","DOI":"10.1038\/s42003-018-0199-z","article-title":"Improved reference genome for the domestic horse increases assembly contiguity and composition","volume":"1","author":"Kalbfleisch","year":"2018","journal-title":"Commun. Biol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1023\/B:CHRO.0000009298.02689.8a","article-title":"Refined genome-wide comparative map of the domestic horse, donkey and human based on cross-species chromosome painting: Insight into the occasional fertility of mules","volume":"12","author":"Yang","year":"2004","journal-title":"Chromosome Res."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"63","DOI":"10.2147\/VMRR.S148542","article-title":"Equine degenerative myeloencephalopathy: Prevalence, impact, and management","volume":"9","author":"Burns","year":"2018","journal-title":"Vet. Med.-Res. Rep."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1063","DOI":"10.1007\/s10815-019-01457-2","article-title":"Down syndrome and infertility: What support should we provide?","volume":"36","author":"Parizot","year":"2019","journal-title":"J. Assist. Reprod. Genet."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"2344","DOI":"10.1056\/NEJMra1706537","article-title":"Down Syndrome","volume":"382","author":"Bull","year":"2020","journal-title":"N. Engl. J. Med."}],"container-title":["Animals"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2615\/12\/7\/803\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T22:40:57Z","timestamp":1760136057000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2615\/12\/7\/803"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,3,22]]},"references-count":41,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2022,4]]}},"alternative-id":["ani12070803"],"URL":"https:\/\/doi.org\/10.3390\/ani12070803","relation":{},"ISSN":["2076-2615"],"issn-type":[{"value":"2076-2615","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,3,22]]}}}