Mutations at these genes can cause congenital limb deformities in humans, including clubfoot and Liebenberg syndrome (Pitx1; Gurnett et al., 2008; Spielmann et al., 2012), and Holt-Oram syndrome (Tbx5; Basson et al., 1997). Here, PITX1 is linked to Brachydactyly - elbow wrist dysplasia.