{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,27]],"date-time":"2026-06-27T07:48:56Z","timestamp":1782546536234,"version":"3.54.5"},"reference-count":15,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2026,6,27]],"date-time":"2026-06-27T00:00:00Z","timestamp":1782518400000},"content-version":"vor","delay-in-days":177,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,1,1]],"date-time":"2026-01-01T00:00:00Z","timestamp":1767225600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["The Scientific World Journal"],"published-print":{"date-parts":[[2026,1]]},"abstract":"<jats:p>Chicken layers are valued for their ability to produce eggs, an essential component of the human diet. Egg characteristics are influenced by genetic factors such as the growth differentiation factor\u20109 (GDF\u20109) gene, which plays a vital role in follicular development and ovulation. Variations in the GDF\u20109 gene can lead to ovulation dysfunction, infertility, and reduced egg quality and production. This systematic review explored the genetic variation of the chicken GDF\u20109 gene and its association with egg characteristics. Following the Preferred Reporting Items for Systematic Reviews and Meta\u2010Analyses (PRISMA) guidelines, databases including ScienceDirect, Google Scholar, PubMed, and Web of Science were used to search for articles using combinations of keywords: \u201cchickens,\u201d \u201cGDF\u20109 gene,\u201d \u201cgenetic variation,\u201d and \u201cegg characteristics.\u201d A total of 106 articles were retrieved, and five met the inclusion criteria. The reviewed studies identified several single nucleotide polymorphisms (SNPs) within the GDF\u20109 gene\u2014namely g.171515C&gt;T, g.171530A&gt;G, g.171529G&gt;A, g.171554C&gt;T, g.171577A&gt;G, g.171600C&gt;T, g.171541A&gt;G, g.171560T&gt;C, and g.171589C&gt;T. Although no identical SNPs were shared among all breeds, these variants were associated with key egg traits such as age at first egg, egg number, and egg weight. The findings suggest that GDF\u20109 gene polymorphisms hold strong potential for use in marker\u2010assisted and genomic selection to enhance reproductive performance and egg\u2010laying efficiency in chickens. However, the current findings are primarily based on conventional genetic association studies, and higher resolution transcriptomic approaches, such as single\u2010cell RNA sequencing, are needed to functionally validate these associations and clarify the molecular mechanisms underlying GDF\u20109 regulation in reproductive traits. Further research using genetically diverse populations and incorporating gene expression analysis is recommended to validate these associations and strengthen the application of GDF\u20109 in poultry breeding.<\/jats:p>","DOI":"10.1155\/tswj\/2659937","type":"journal-article","created":{"date-parts":[[2026,6,27]],"date-time":"2026-06-27T07:43:41Z","timestamp":1782546221000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Genetic Variation of Chicken\n                    <i>Growth Differentiation Factor-9<\/i>\n                    Gene and Association With Egg Characteristics: A Systematic Review"],"prefix":"10.1155","volume":"2026","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-6427-7396","authenticated-orcid":false,"given":"Lehlogonolo Joel Morumbula","family":"Maake","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-6982-6317","authenticated-orcid":false,"given":"Salome","family":"Mhlabini","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9616-3784","authenticated-orcid":false,"given":"Travor Tshepiso","family":"Magonyane","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-7090-0245","authenticated-orcid":false,"given":"Raisibe Lisbert","family":"Mahlo","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5739-7991","authenticated-orcid":false,"given":"Madumetja Cyril","family":"Mathapo","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3519-7806","authenticated-orcid":false,"given":"Thobela Loius","family":"Tyasi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,6,27]]},"reference":[{"key":"e_1_2_10_1_2","doi-asserted-by":"publisher","DOI":"10.1155\/2022\/1393392"},{"key":"e_1_2_10_2_2","doi-asserted-by":"publisher","DOI":"10.1399\/eps.2016.117"},{"key":"e_1_2_10_3_2","doi-asserted-by":"publisher","DOI":"10.3382\/ps\/peu083"},{"key":"e_1_2_10_4_2","doi-asserted-by":"publisher","DOI":"10.1155\/2018\/4963834"},{"key":"e_1_2_10_5_2","doi-asserted-by":"publisher","DOI":"10.1111\/jbg.12086"},{"key":"e_1_2_10_6_2","doi-asserted-by":"publisher","DOI":"10.3389\/fgene.2021.602583"},{"key":"e_1_2_10_7_2","doi-asserted-by":"publisher","DOI":"10.1080\/00071668.2015.1019829"},{"key":"e_1_2_10_8_2","doi-asserted-by":"publisher","DOI":"10.5195\/jmla.2018.345"},{"key":"e_1_2_10_9_2","doi-asserted-by":"publisher","DOI":"10.1186\/s13643-021-01671-z"},{"key":"e_1_2_10_10_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.angen.2023.200147"},{"key":"e_1_2_10_11_2","doi-asserted-by":"publisher","DOI":"10.1080\/10495398.2018.1516222"},{"key":"e_1_2_10_12_2","doi-asserted-by":"publisher","DOI":"10.3382\/ps\/peu023"},{"key":"e_1_2_10_13_2","first-page":"617","article-title":"Association of Growth Differentiation Factor-9 (GDF-9) Gene With Birth Type, In Vitro Maturation and Selected Physiological Traits in Awassi Sheep","volume":"13","author":"Hassooni H. A.","year":"2023","journal-title":"Journal of Animal Health and Production"},{"key":"e_1_2_10_14_2","doi-asserted-by":"publisher","DOI":"10.1016\/bs.vh.2017.12.003"},{"key":"e_1_2_10_15_2","doi-asserted-by":"publisher","DOI":"10.3390\/biom13010047"}],"container-title":["The Scientific World Journal"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1155\/tswj\/2659937","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/full-xml\/10.1155\/tswj\/2659937","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1155\/tswj\/2659937","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,27]],"date-time":"2026-06-27T07:43:42Z","timestamp":1782546222000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1155\/tswj\/2659937"}},"subtitle":[],"editor":[{"given":"Mugimane","family":"Manjanatha","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2026,1]]},"references-count":15,"journal-issue":{"issue":"1","published-print":{"date-parts":[[2026,1]]}},"alternative-id":["10.1155\/tswj\/2659937"],"URL":"https:\/\/doi.org\/10.1155\/tswj\/2659937","archive":["Portico"],"relation":{},"ISSN":["2356-6140","1537-744X"],"issn-type":[{"value":"2356-6140","type":"print"},{"value":"1537-744X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,1]]},"assertion":[{"value":"2026-01-19","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-06-13","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-06-27","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"2659937"}}