Figure 3. Agglomerative clustering of a genetic distance matrix to show the relationship between cellular proliferation in the hippocampus (KI67), behaviour, and other phenotypes obtained in the heterogeneous stock mice.

The distance matrix is based on the degree of QTL overlap. In order to simplify the presentation, the 97 phenotypes were grouped into 16 trait sets according to the disease models that they were designed to test, or on their physiological functions (for instance, combining all QTLs for T cell function or for hippocampal function). Species typical behaviour, burrowing, has been shown to be affected by hippocampal lesions yet does not reflect emotional reactivity [48].