The Ay allele at the agouti locus reduces the size and alters the shape of the mandible in mice

To confirm my previous findings that the A(y) allele at the agouti locus reduced the mandible size and therefore altered the mandible shape in a KK mouse strain background, I further investigated the effects of the A(y) allele on mandible morphology on different strain backgrounds, DDD and B6. Principal component analysis revealed that the mandible was significantly smaller in A(y) mice (DDD-A(y) and B6-A(y)) than in corresponding non-A(y) mice (DDD and B6, respectively). Discriminant and canonical discriminant analyses revealed that most mice were classified correctly in their own strains, and misclassification was not observed between DDD (-A(y)) and B6 (-A(y)). The results confirmed that the A(y) allele reduced the mandible size and altered the mandible shape regardless of the strain background. However, the difference in mandible morphology between A(y) mice and the corresponding non-A(y) mice within a strain was not as large as that which intrinsically underlay the two strains. Possible mechanisms of the A(y) action are discussed.