In mammals, Twist1 and Twist2 paralogs are known for playing a major role in the inhibition of differentiation of mesenchymal cell lineages, particularly in bone, muscle and dermis [4–7] The maintenance of functional Twist proteins throughout evolution has been of great importance since mutations in Twist genes and improper regulation of genes that are targeted by these transcription factors can result in human diseases such as Setleis Syndrome [8], Barber-Say Syndrome and Ablepharon Macrostomia [9], Saethre Chotzen syndrome [10,11], inflammatory diseases [12] and cancer [13,14]. The gene discussed is TWIST1; the disease is Saethre-Chotzen syndrome.