TAILIEUCHUNG - Báo cáo sinh học: "Genomic evaluations with many more genotypes"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học quốc tế đề tài: Genomic evaluations with many more genotypes | VanRaden et al. Genetics Selection Evolution 2011 43 10 http content 43 1 10 GSE Ge n et i cs Selection Evolution RESEARCH Open Access Genomic evaluations with many more genotypes 1 2 1 3 Paul M VanRaden Jeffrey R O Connell George R Wiggans Kent A Weigel Abstract Background Genomic evaluations in Holstein dairy cattle have quickly become more reliable over the last two years in many countries as more animals have been genotyped for 50 000 markers. Evaluations can also include animals genotyped with more or fewer markers using new tools such as the 777 000 or 2 900 marker chips recently introduced for cattle. Gains from more markers can be predicted using simulation whereas strategies to use fewer markers have been compared using subsets of actual genotypes. The overall cost of selection is reduced by genotyping most animals at less than the highest density and imputing their missing genotypes using haplotypes. Algorithms to combine different densities need to be efficient because numbers of genotyped animals and markers may continue to grow quickly. Methods Genotypes for 500 000 markers were simulated for the 33 414 Holsteins that had 50 000 marker genotypes in the North American database. Another 86 465 non-genotyped ancestors were included in the pedigree file and linkage disequilibrium was generated directly in the base population. Mixed density datasets were created by keeping 50 000 every tenth of the markers for most animals. Missing genotypes were imputed using a combination of population haplotyping and pedigree haplotyping. Reliabilities of genomic evaluations using linear and nonlinear methods were compared. Results Differing marker sets for a large population were combined with just a few hours of computation. About 95 of paternal alleles were determined correctly and 95 of missing genotypes were called correctly. Reliability of breeding values was already high with 50 000 simulated markers. The gain in reliability from increasing

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