Accuracy of whole-genome sequence genotype imputation in a layer line
Résumé
Over the past several years, high-density genotyping has led to major advances in genomic selection and understanding of genomes. This is also the case in laying hens with the availability of the Affymetrix HD 600K chip since 2013. Nowadays, NGS costs are becoming more and more affordable. Based on the HD SNP chip, the use of imputation to go back to the sequence level then makes it possible to obtain information on millions of polymorphisms for a large number of individuals. In this study, we analyzed the quality of the imputation of the HD chip genotypes on sequence genotypes for 90 individuals of a layer line presenting the 2 types of information. After quality control, these individuals presented genotypes for 290K and more than 6 million SNPs respectively with 600K genotyping and 20X sequencing. We carried out a cross-validation with 8 draws of 5 individuals. The correlation between true and imputed genotypes was between 0.96 and 0.99 depending on the individual.
Correlations were greater than 0.90 for all chromosomes except chromosomes 16 and 25. After this validation work, we imputed an additional set of 95 individuals to perform GWAS. These analyses confirmed some QTLs of interest as a QTL of egg shell color on chromosome 7 and a QTL of egg shell strength on chromosome 1.