The current study design incorporates two previously developed, non-invasive approaches to characterize the phenotype of individuals affected with XLHED. Facial 3-dimensional (3D) imaging will be created from white-field morphometric scanning (Hammond, 2004. The 3D facial photographs collected from males (ages 4 years and up) will be used to develop a non-invasive screening tool, which could enable detection of craniofacial signs of XLHED in the newborn period. 3D facial profiling has been reported to be effective in identifying HED (Dellavia et al., 2008), but the technology does not yet meet the ease-of-use criteria for a universal screening tool.