Analysis of the genetic association between face breadth and maxillary arch width using SMXA recombinant inbred mouse strains

We measured the face breadth and the maxillary arch width of a total of 230 mice from 21 SMXA recombinant inbred (RI) mouse strains and their parental strains SM/J and A/J, and investigated genetic factors associated with these parameters. The coefficient of variation between maxillary arch width and face breadth within the same strain was low, suggesting that this is strictly governed by genetic factors. Maxillary arch width and face breadth exhibited a continuous size distribution within the 23 strains, suggesting the involvement of multiple genes rather than a single gene. In the 21 strains of SMXA RI mice and strains SM/J and A/J, there was a significant correlation between face breadth and maxillary arch width in male mice, with a correlation coefficient of 0.52. We performed a genome-wide scan for quantitative trait loci (QTL) determining maxillary arch width and face breadth. With respect to face breadth, the logarithm of odds (Lod) score for D11Mit229 on chromosome 11 was significant for both males and females, suggesting that the genes determining face breadth are located in this region. Although no loci exhibiting a significant Lod score were detected for maxillary arch width, the highest Lod scores were detected for the same loci as for face breadth. These findings suggest that some of the genes that determine face breadth may be the same genes that determine maxillary arch width.