RPS6KA3 and X-linked hypohidrotic ectodermal dysplasia: The dental phenotype of the Rsk2-/Y mouse resembles that encountered in the tabby mouse (a model for X-linked hypohidrotic ectodermal dysplasia- an ectodermal dysplasia characterized by an absence or dystrophic development of hair, nail, sweat- lacrymal- mammary- glands and tooth; OMIM #305100).