Mapping quantitative trait loci for body weight on the X chromosome in mice. I. Analysis of a reciprocal F2 population.
Evidence of a large sex-linked effect accounting for 25% of the divergence between mouse lines selected for body weight has been described previously. A marker-based study was undertaken to determine the number and map positions of the putative X-linked quantitative trait loci (QTLs). An F2 population was generated from a reciprocal F1 between an inbred low line derived from the low selection line and the high selection line. To enable inference of marker-associated QTL effects on the X chromosome, an analytical technique was developed based on the multiple regression method of Haley and Knott. The analysis of data on 10 week weight indicated a single QTL of large effect situated at about 23 cM from the proximal end of the chromosome, with a peak LOD score of 24.4. The likelihood curve showed a single well-defined peak, and gave a 95% confidence interval for the QTL location of 8 cM. The estimates for the additive genotypic effects in males and females (half the differences between hemizygous males and between homozygous females) were 2.6 g in both cases, or 17% and 20% of the 10 week body weight in males and females respectively. Dominance effects in the females were found to be non-significant. No significant X-linked effect on carcass fat percentage was detected, but a single X-linked QTL appears to explain almost the entire X-linked body weight effect.
Rance
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Institute of Cell, Animal and Population Biology, University of Edinburgh, Scotland, UK.
Hill
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Keightley
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D000273:Adipose Tissue / Q000033:anatomy & histology; D000818:Animals; D001835:Body Weight / Q000235:genetics*; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D005260:Female; D005838:Genotype; D008297:Male; D051379:Mice / Q000033:anatomy & histology / Q000235:genetics*; D008815:Mice, Inbred Strains; D010641:Phenotype; D019655:Quantitative Trait, Heritable; D014960:X Chromosome / Q000235:genetics*