Experiment
A novel approach was used to identify QTLs involved in mandible formation in the mouse, a trait influenced by several subtle and additive factors difficult to detect by traditional QTL analysis. 535 (SM/J x LG/J)F2 intercross animals at 70 days of age were typed for 76 markers at an average resolution of 27.5 cM. SM/J is a strain with characteristically small body size while the LG/J is large in body size. Digitized images of mandibles from sacrificed animals were analyzed for association with QTLs influencing multivariate spacial aspects of mandible formation, such as size, shape, and symmetry. 12 QTLs influencing mandible size (Manz1-12), 25 QTLs influencing mandible shape (Manh1-25), and 5 QTLs influencing mandible symmetry (Many1-5) were identified.The QTLs identified in this study appear to correspond to mandible morphology QTLs previously identified using traditional QTL analysis by Leamy (1997; J:42413) and Cheverud (1997; J:46024). The authors state that direct comparisons between the previously identified mandible morphology QTLs and QTLs identified in the current study (Manz1-12, Manh1-25, and Many1-5) are difficult to make, and that the correlations remain informal.
Analysis Tools