Our studies also indicate that jaw associated muscles, including the masseter, temporalis, and pterygoids, were deficient and abnormally positioned in the absence of Foxc1. This reduction in size of the muscles of mastication is very similar to the decrease in muscle volume of the masseter, temporalis, and pterygoid reported in human hemifacial microsomia patients [62]–[65]. The gene discussed is FOXC1; the disease is craniofacial microsomia.