APOE and familial hypercholesterolemia: However, an increase in the thickness of the aortic wall is noted to some extent in the hypertensive C57 mouse and especially in the hypercholesterolemic apoE-/- mouse, and the concurrence of both factors (hypercholesterolemia and hypertension) is observed to exert an additive effect on the aortic wall thickness in the apoE-/- mouse [42].