Abnormal segregation of alleles and haplotypes at the polymorphic site of the PRNP gene within promoter and intron 1 regions in Polish Holstein-Friesian cattle

Allele and haplotype segregation at the polymorphic sites within the promoter (23indel) and intron 1 (12indel) regions of the PRNP gene was analyzed in Polish Holstein-Friesian cattle. More 23del/del homozygotes and fewer 23ins/ins homozygotes than expected were observed in the offspring of ♂ 23ins/del × ♀ 23ins/del parents. In the offspring of ♂ 23ins/del × ♀ 23del/del parents and ♂ 23del/del × ♀ 23ins/del parents, a trend toward more 23del/del animals and fewer 23ins/del animals than expected was noted. At the 12indel polymorphic site, the only trend found was one toward fewer 12ins/ins genotypes and more 12ins/del and 12del/del genotypes than expected in the offspring of ♂ 12ins/del × ♀ 12ins/del parents. An analysis of haplotype segregation revealed more 23del-12del/23del-12del diplotypes and fewer 23ins-12ins/23ins-12ins diplotypes at the significance threshold than expected in the offspring of ♂ 23ins-12ins/23del-12del × ♀ 23ins-12ins/23del-12del parents.

Mapping of multiple quantitative trait loci affecting bovine spongiform encephalopathy

A whole-genome scan was conducted to map quantitative trait loci (QTL) for BSE resistance or susceptibility. Cows from four half-sib families were included and 173 microsatellite markers were used to construct a 2835-cM (Kosambi) linkage map covering 29 autosomes and the pseudoautosomal region of the sex chromosome. Interval mapping by linear regression was applied and extended to a multiple-QTL analysis approach that used identified QTL on other chromosomes as cofactors to increase mapping power. In the multiple-QTL analysis, two genome-wide significant QTL (BTA17 and X/Y(ps)) and four genome-wide suggestive QTL (BTA1, 6, 13, and 19) were revealed. The QTL identified here using linkage analysis do not overlap with regions previously identified using TDT analysis. One factor that may explain the disparity between the results is that a more extensive data set was used in the present study. Furthermore, methodological differences between TDT and linkage analyses may affect the power of these approaches.