Summary

Association mapping seeks for markers at vicinity of genes affecting on complex traits. Family based association studies extensively used in human genetics for mapping genes. Discordant Sib Pair (DSP) design has advantages in controlling population stratification. The main aim of this paper was to investigate relation between number of discordant sib pairs to association mapping using QTL-MAS 2010 simulated dataset. The pedigree included four generations with 2326 individuals for quantitative trait. The genome consisted of 10031 Single Nucleotide Polymorphisms (SNPs) distributed over 5 chromosomes. We used mixed model to perform genome wide association analyses. In addition count of marker alleles in the affected and unaffected sib pairs contrasted to detect putative association. Most of the QTLs were located at chromosome 1 and 3. Genome based heritability were found to be more accurate compared with traditional pedigree based estimates of heritability. Since error rate decreases with increasing number of sib pairs the increasing proportions of success rate is not surprising. It is much more likely to have larger number of sib pairs in animal genetics compared with human genetics. Hence we believe that discordant sib pair approach might be useful for association mapping in domestic species