{"title":"纯合子系作为血统同一性度量的性质。","authors":"Oda B Wæge, Tom Druet, Peer Berg, Theo Meuwissen","doi":"10.1111/jbg.70013","DOIUrl":null,"url":null,"abstract":"<p><p>Runs of Homozygosity (ROH) are commonly used to quantify autozygosity/identity-by-descent (IBD) in an individual or population. However, the method's accuracy at the segment level in livestock populations has only been evaluated in a few studies. Thus, the aim of this study was to determine to what extent ROH are truly IBD and estimate the proportion of IBD segments that go undetected in a simulated livestock population. We simulated a population of randomly mating animals for 100 generations. The genome consisted of a single chromosome with a SNP density of either 46 or 92 SNPs per mega base (Mb). In addition, a set of founder markers tracing IBD was recorded. ROH were detected using four different parameter combinations. Using the two sets of markers, we calculated the true positive rate, power, and overall correlation between true (F<sub>IBD</sub>) and estimated inbreeding (F<sub>ROH</sub>). Additionally, a new measure for within-ROH inbreeding (F|ROH) was introduced and calculated the level of homozygosity within a ROH compared to the general expectation in the genome. The results indicate that ROH longer than 2 Mb are a reliable indicator of IBD, with the F|ROH being over 0.9 for all ROH lengths and parameter combinations. True positive rates only exceeded 0.9 consistently for ROH over 9 Mb, indicating that many of the identified ROH may be associated with common ancestors more ancient than the base population. The power was mainly controlled by the parameter stringency, that is, allowing for shorter ROH increased the power. The ROH-based individual measure of inbreeding F<sub>ROH</sub> was highly correlated to F<sub>IBD</sub> while also having regression coefficients close to 1 (i.e., a 1% variation in F<sub>ROH</sub> corresponded to a 1% variation in F<sub>IBD</sub>). Using stringent ROH parameters resulted in underestimation of the rate of inbreeding in the population. Increasing marker density improved predictions, including a higher true positive rate, power, higher correlations, and less underestimation of inbreeding rates.</p>","PeriodicalId":54885,"journal":{"name":"Journal of Animal Breeding and Genetics","volume":" ","pages":""},"PeriodicalIF":1.9000,"publicationDate":"2025-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Properties of Runs of Homozygosity as a Measure of Identity by Descent.\",\"authors\":\"Oda B Wæge, Tom Druet, Peer Berg, Theo Meuwissen\",\"doi\":\"10.1111/jbg.70013\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>Runs of Homozygosity (ROH) are commonly used to quantify autozygosity/identity-by-descent (IBD) in an individual or population. However, the method's accuracy at the segment level in livestock populations has only been evaluated in a few studies. Thus, the aim of this study was to determine to what extent ROH are truly IBD and estimate the proportion of IBD segments that go undetected in a simulated livestock population. We simulated a population of randomly mating animals for 100 generations. The genome consisted of a single chromosome with a SNP density of either 46 or 92 SNPs per mega base (Mb). In addition, a set of founder markers tracing IBD was recorded. ROH were detected using four different parameter combinations. Using the two sets of markers, we calculated the true positive rate, power, and overall correlation between true (F<sub>IBD</sub>) and estimated inbreeding (F<sub>ROH</sub>). Additionally, a new measure for within-ROH inbreeding (F|ROH) was introduced and calculated the level of homozygosity within a ROH compared to the general expectation in the genome. The results indicate that ROH longer than 2 Mb are a reliable indicator of IBD, with the F|ROH being over 0.9 for all ROH lengths and parameter combinations. True positive rates only exceeded 0.9 consistently for ROH over 9 Mb, indicating that many of the identified ROH may be associated with common ancestors more ancient than the base population. The power was mainly controlled by the parameter stringency, that is, allowing for shorter ROH increased the power. The ROH-based individual measure of inbreeding F<sub>ROH</sub> was highly correlated to F<sub>IBD</sub> while also having regression coefficients close to 1 (i.e., a 1% variation in F<sub>ROH</sub> corresponded to a 1% variation in F<sub>IBD</sub>). Using stringent ROH parameters resulted in underestimation of the rate of inbreeding in the population. Increasing marker density improved predictions, including a higher true positive rate, power, higher correlations, and less underestimation of inbreeding rates.</p>\",\"PeriodicalId\":54885,\"journal\":{\"name\":\"Journal of Animal Breeding and Genetics\",\"volume\":\" \",\"pages\":\"\"},\"PeriodicalIF\":1.9000,\"publicationDate\":\"2025-08-27\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Animal Breeding and Genetics\",\"FirstCategoryId\":\"97\",\"ListUrlMain\":\"https://doi.org/10.1111/jbg.70013\",\"RegionNum\":3,\"RegionCategory\":\"农林科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"AGRICULTURE, DAIRY & ANIMAL SCIENCE\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Animal Breeding and Genetics","FirstCategoryId":"97","ListUrlMain":"https://doi.org/10.1111/jbg.70013","RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"AGRICULTURE, DAIRY & ANIMAL SCIENCE","Score":null,"Total":0}
Properties of Runs of Homozygosity as a Measure of Identity by Descent.
Runs of Homozygosity (ROH) are commonly used to quantify autozygosity/identity-by-descent (IBD) in an individual or population. However, the method's accuracy at the segment level in livestock populations has only been evaluated in a few studies. Thus, the aim of this study was to determine to what extent ROH are truly IBD and estimate the proportion of IBD segments that go undetected in a simulated livestock population. We simulated a population of randomly mating animals for 100 generations. The genome consisted of a single chromosome with a SNP density of either 46 or 92 SNPs per mega base (Mb). In addition, a set of founder markers tracing IBD was recorded. ROH were detected using four different parameter combinations. Using the two sets of markers, we calculated the true positive rate, power, and overall correlation between true (FIBD) and estimated inbreeding (FROH). Additionally, a new measure for within-ROH inbreeding (F|ROH) was introduced and calculated the level of homozygosity within a ROH compared to the general expectation in the genome. The results indicate that ROH longer than 2 Mb are a reliable indicator of IBD, with the F|ROH being over 0.9 for all ROH lengths and parameter combinations. True positive rates only exceeded 0.9 consistently for ROH over 9 Mb, indicating that many of the identified ROH may be associated with common ancestors more ancient than the base population. The power was mainly controlled by the parameter stringency, that is, allowing for shorter ROH increased the power. The ROH-based individual measure of inbreeding FROH was highly correlated to FIBD while also having regression coefficients close to 1 (i.e., a 1% variation in FROH corresponded to a 1% variation in FIBD). Using stringent ROH parameters resulted in underestimation of the rate of inbreeding in the population. Increasing marker density improved predictions, including a higher true positive rate, power, higher correlations, and less underestimation of inbreeding rates.
期刊介绍:
The Journal of Animal Breeding and Genetics publishes original articles by international scientists on genomic selection, and any other topic related to breeding programmes, selection, quantitative genetic, genomics, diversity and evolution of domestic animals. Researchers, teachers, and the animal breeding industry will find the reports of interest. Book reviews appear in many issues.