Mapping and exclusion mapping of genomic imprinting effects in mouse F2 families

Parent-of-origin effects were mapped by multimarker regression analysis in a cross between a high body weight selected line (DU6) and a control line (DUKs). The difference between F(2) progeny being heterozygous Qq and qQ (first allele is paternally derived) for grandpaternal Q and grandmaternal q alleles was genome-wide significant for the traits liver weight and spleen weight with a paternal imprinting effect at 1 cM on proximal chromosome 11. Suggestive imprinting effects (chromosome-wide error probability less than 0.05) were found for the traits body weight, liver weight, and kidney weight, and were located on chromosome 14 at 25 cM, 23 cM, and 32 cM, respectively. A genome-wide significant quantitative trait locus (QTL) for spleen weight at 26 cM slightly failed the suggestive significance level for imprinting. The effect was consistently maternal for all these traits on chromosome 14. Further suggestive imprinting effects were found for abdominal fat percentage on chromosome 3, for spleen weight on chromosome 5, and for liver weight on chromosome X. Our results are supported by a likely imprinting in a human genome region with homology to mouse chromosome 14 and agree well with the known imprinting of proximal chromosome 11 in the mouse.