Haploinsufficiency of the syntenic region containing TBX3 and MED13L (Jin et al. 2013) has been reported to cause short stature, developmental delay, and intellectual disability, among other conditions in humans (Adegbola et al. 2015), and is established as a major contributor to height in horses (Kader et al. 2016). Here, TBX3 is linked to Global developmental delay.