title: Body composition and gene expression QTL mapping in mice reveals imprinting and interaction effects.
abstract: BACKGROUND
  Shifts in body composition, such as accumulation of body fat, can be a symptom of many chronic human diseases; hence, efforts have been made to investigate the genetic mechanisms that underlie body composition. For example, a few quantitative trait loci (QTL) have been discovered using genome-wide association studies, which will eventually lead to the discovery of causal mutations that are associated with tissue traits. Although some body composition QTL have been identified in mice, limited research has been focused on the imprinting and interaction effects that are involved in these traits. Previously, we found that Myostatin genotype, reciprocal cross, and sex interacted with numerous chromosomal regions to affect growth traits.
  
  
  RESULTS
  Here, we report on the identification of muscle, adipose, and morphometric phenotypic QTL (pQTL), translation and transcription QTL (tQTL) and expression QTL (eQTL) by applying a QTL model with additive, dominance, imprinting, and interaction effects. Using an F2 population of 1000 mice derived from the Myostatin-null C57BL/6 and M16i mouse lines, six imprinted pQTL were discovered on chromosomes 6, 9, 10, 11, and 18. We also identified two IGF1 and two Atp2a2 eQTL, which could be important trans-regulatory elements. pQTL, tQTL and eQTL that interacted with Myostatin, reciprocal cross, and sex were detected as well. Combining with the additive and dominance effect, these variants accounted for a large amount of phenotypic variation in this study.
  
  
  CONCLUSIONS
  Our study indicates that both imprinting and interaction effects are important components of the genetic model of body composition traits. Furthermore, the integration of eQTL and traditional QTL mapping may help to explain more phenotypic variation than either alone, thereby uncovering more molecular details of how tissue traits are regulated.
authors.forename: Ye
authors.initials: Y
authors.lastname: Cheng
authors.forename: Satyanarayana
authors.initials: S
authors.lastname: Rachagani
authors.forename: Angela
authors.initials: A
authors.lastname: Cánovas
authors.forename: Mary Sue
authors.initials: MS
authors.lastname: Mayes
authors.forename: Richard G
authors.initials: RG
authors.lastname: Tait
authors.forename: Jack C M
authors.initials: JC
authors.lastname: Dekkers
authors.affiliation: Department of Animal Science, Iowa State University, 2255 Kildee, Ames, IA, USA. jreecy@iastate.edu.
authors.forename: James M
authors.initials: JM
authors.lastname: Reecy
mesh_terms: D050154:Adiposity / Q000235:genetics; D000818:Animals; D001823:Body Composition / Q000235:genetics*; D002874:Chromosome Mapping; D002875:Chromosomes; D005260:Female; D014644:Genetic Variation; D018392:Genomic Imprinting; D005838:Genotype; D007334:Insulin-Like Growth Factor I / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D055435:Myostatin / Q000172:deficiency / Q000235:genetics; D010641:Phenotype; D040641:Quantitative Trait Loci; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000235:genetics
chemical_list: D055435:Myostatin; C519530:insulin-like growth factor-1, mouse; D007334:Insulin-Like Growth Factor I; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C506947:Atp2a2 protein, mouse