Patients with activating FGFR3 mutations exhibit skeletal dysplasias characterized by short stature including achondroplasia (ACH, OMIM 100800), thanatophoric dysplasia I/ II (TD I, OMIM 187600 and TD II,OMIM 187601), hypochondroplasia (OMIM 146000), and severe ACH with developmental delay with acanthosis nigricans (SADDAN, OMIM 187600) [27]. This evidence concerns the gene FGFR3 and thanatophoric dysplasia.