Editing Przewalski's horse (section)

===Genomics===
The [[karyotype]] of Przewalski's horse differs from that of the domestic horse, having 33&nbsp;chromosome pairs versus&nbsp;32, apparently due to a [[Fission (biology)|fission]] of a large chromosome ancestral to domestic horse chromosome&nbsp;5 to produce Przewalski's horse chromosomes&nbsp;23 and 24,<ref name=Piras>{{cite journal |last1=Piras |first1=F.M. |last2=Nergadze |first2=S.G. |last3=Poletto |first3=V. |last4=Cerutti |first4=F. |last5=Ryder |first5=O.A. |last6=Leeb |first6=T. |last7=Raimondi |first7=E. |last8=Giulotto |first8=E. |title=Phylogeny of Horse Chromosome 5q in the Genus Equus and Centromere Repositioning |journal=Cytogenetic and Genome Research |year=2009 |volume=126 |issue=1–2 |pages=165–172 |doi=10.1159/000245916 |pmid=20016166 |s2cid=24884868 |url=https://boris.unibe.ch/38295/ |archive-date=29 October 2023 |access-date=17 September 2023 |archive-url=https://web.archive.org/web/20231029195550/https://boris.unibe.ch/38295/ |url-status=live }}</ref> though conversely, a [[Robertsonian translocation]] that fused two chromosomes ancestral to those seen in Przewalski's horse to produce the single large domestic horse chromosome has also been proposed.<ref name=Huang>{{cite journal |last1=Huang |first1=Jinlong |last2=Zhao |first2=Yiping |last3=Shiraigol |first3=Wunierfu |last4=Li |first4=Bei |last5=Bai |first5=Dongyi |last6=Ye |first6=Weixing |last7=Daidiikhuu |first7=Dorjsuren |last8=Yang |first8=Lihua |last9=Jin |first9=Burenqiqige |last10=Zhao |first10=Qinan |last11=Gao |first11=Yahan |last12=Wu |first12=Jing |last13=Bao |first13=Wuyundalai |last14=Li |first14 = Anaer |last15=Zhang |first15=Yuhong |last16=Han |first16=Haige |last17=Bai |first17=Haitang |last18=Bao |first18=Yanqing |last19=Zhao |first19=Lele |last20=Zhai |first20=Zhengxiao |last21=Zhao |first21=Wenjing |last22=Sun |first22=Zikui |last23=Zhang |first23=Yan |last24=Meng |first24=He |last25=Dugarjaviin |first25=Manglai |display-authors=6 |year=2015 |title=Analysis of horse genomes provides insight into the diversification and adaptive evolution of karyotype |journal=Scientific Reports |volume=4 |page=4958 |pmid=24828444 |pmc=4021364 |doi=10.1038/srep04958 |url=}}</ref>

Many smaller [[Chromosomal inversion|inversions]], [[Insertion (genetics)|insertions]] and other rearrangements were observed between the chromosomes of domestic and Przewalski's horses, while there was much lower hetero[[zygosity]] in Przewalski's horses, with extensive segments devoid of genetic diversity, a consequence of the recent severe [[Population bottleneck|bottleneck]] of the captive Przewalski's horse population.<ref name=Huang/> In comparison, the chromosomal differences between domestic horses and [[zebra]]s include numerous large-scale [[Chromosomal translocation|translocations]], fusions, inversions, and [[centromere]] repositioning.<ref name=Piras/> Przewalski's horse has the highest [[diploid]] chromosome number among all equine species. They can interbreed with the domestic horse and produce fertile offspring, with 65&nbsp;chromosomes.<ref name="lau 2009 199–208"/>

The mitochondrial genome has 37 genes that are 99.63% identical to that of the domestic horse.<ref>{{cite journal |last1=Flack |first1=Nicole |last2=Hughes |first2=Lauren |last3=Cassens |first3=Jacob |last4=Enriquez |first4=Maya |last5=Gebeyehu |first5=Samrawit |last6=Alshagawi |first6=Mohammed |last7=Hatfield |first7=Jason |last8=Kauffman |first8=Anna |last9=Brown |first9=Baylor |last10=Klaeui |first10=Caitlin |last11=Mabrouk |first11=Islam F |last12=Walls |first12=Carrie |last13=Yeater |first13=Taylor |last14=Rivas |first14=Anne |last15=Faulk |first15=Christopher |title=The genome of Przewalski's horse ( Equus ferus przewalskii ) |journal=G3: Genes, Genomes, Genetics |date=28 May 2024 |volume=14 |issue=8 |pages=jkae113 |doi=10.1093/g3journal/jkae113|doi-access=free |pmid=38805182 |pmc=11304947 }}</ref>