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These processes are primarily mediated by activation-induced cytidine deaminase (AID). Gene conversion generates diversity in immunoglobulin heavy and light chains (IGHVs) in species such as chickens and rabbits, though it has not been widely studied. Since 80% of the equine IGHV repertoire originates from only three functional gene segments, we examined gene conversion events in horses to assess their role in antibody diversification. Using a modified version of BrepConvert, which optimized analysis time, we identified gene conversion events in 6.9% of immunoglobulin sequences. The results showed a local preference, with most events occurring at the beginning of framework region 1 (FR1) and within complementarity-determining region 2 (CDR2). Pseudogenes IGHV4-35, IGHV4-53, and IGHV4-38 were utilized most frequently, while functional genes IGHV4-21, IGHV4-22, and IGHV4-29 exhibited the highest event frequencies. Interestingly, while most mismatched regions were only three nucleotides long, 91% of these events are flanked by specific sequences (six nucleotides at the 5\u2032 end and one nucleotide at the 3\u2032 end). Furthermore, functional pseudogene pairs often share identical leader regions of 5\u201326 nucleotides, suggesting expanded events. We also identified a potential association between these events and local non-B DNA conformations, as well as with the zinc finger protein ZNF691, which supports the involvement of DNA-binding factors. Together, these findings demonstrate that gene conversion significantly contributes to equine antibody diversity by targeting specific IGHV regions.<\/jats:p>","DOI":"10.1007\/s00251-026-01400-7","type":"journal-article","created":{"date-parts":[[2026,5,19]],"date-time":"2026-05-19T00:33:43Z","timestamp":1779150823000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Identification of gene conversion events in horse IGHV suggests preferential hotspots for diversification"],"prefix":"10.1007","volume":"78","author":[{"given":"Juliana Edelvacy Lima","family":"Pinto","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jo\u00e3o Henrique Brand\u00e3o","family":"Gerv\u00e1sio","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joseph Chi-fung","family":"Ng","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Adriano","family":"Gomes-Silva","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Herbert L.","family":"de Matos Guedes","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Luiz","family":"Cunha","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Leda R.","family":"Castilho","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jerson Lima","family":"da Silva","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gl\u00f3ria Regina","family":"Franco","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Carlena","family":"Navas","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Liza Figueiredo","family":"Felicori","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"297","published-online":{"date-parts":[[2026,5,19]]},"reference":[{"key":"1400_CR1","doi-asserted-by":"publisher","first-page":"26","DOI":"10.4172\/1745-7580.1000054","volume":"8","author":"E Alamyar","year":"2012","unstructured":"Alamyar E, Giudicelli V, Li S, Duroux P, Lefranc MP (2012) IMGT\/HighV-QUEST: the IMGT\u00ae web portal for immunoglobulin (IG) or antibody and T cell receptor (TR) analysis from NGS high throughput and deep sequencing. 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