tailieunhanh - Báo cáo sinh học: "Quantitative estimation of genetic risk for atypical scrapie in French sheep and potential consequences of the current breeding programme for resistance to scrapie on the risk of atypical scrapie"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học quốc tế đề tài: Quantitative estimation of genetic risk for atypical scrapie in French sheep and potential consequences of the current breeding programme for resistance to scrapie on the risk of atypical scrapie | Fediaevsky et al. Genetics Selection Evolution 2010 42 14 http content 42 1 14 GSE Ge n et i cs Selection Evolution RESEARCH Open Access Quantitative estimation of genetic risk for atypical scrapie in French sheep and potential consequences of the current breeding programme for resistance to scrapie on the risk of atypical scrapie Alexandre Fediaevsky 1 2 Didier Calavas2 Patrick Gasqui1 Katayoun Moazami-Goudarzi3 Pascal Laurent3 Jean-Noel Arsac2 Christian Ducrot1 and Carole Moreno4 Abstract Background Since 2002 active surveillance programmes have detected numerous atypical scrapie AS and classical scrapie cases CS in French sheep with almost all the PrP genotypes. The aim of this study was 1 to quantify the genetic risk of AS in French sheep and to compare it with the risk of CS 2 to quantify the risk of AS associated with the increase of the ARR allele frequency as a result of the current genetic breeding programme against CS. Methods We obtained genotypes at codons 136 141 154 and 171 of the PRNP gene for representative samples of 248 AS and 245 CS cases. We used a random sample of 3 317 scrapie negative animals genotyped at codons 136 154 and 171 and we made inferences on the position 141 by multiple imputations using external data. To estimate the risk associated with PrP genotypes we fitted multivariate logistic regression models and we estimated the prevalence of AS for the different genotypes. Then we used the risk of AS estimated for the ALRR-ALRR genotype to analyse the risk of detecting an AS case in a flock homogenous for this genotype. Results Genotypes most at risk for AS were those including an AFRQ or ALHQ allele while genotypes including a VLRQ allele were less commonly associated with AS. Compared to ALRQ-ALRQ the ALRR-ALRR genotype was significantly at risk for AS and was very significantly protective for CS. The prevalence of AS among ALRR-ALRR animals was o and was not different from the prevalence in the general .