FGFR3 and Costello syndrome: Whilst this is an unusual situation, it is not unique to FGFR2 and similar cases have been documented for FGFR3 mutations in achondroplasia [Henderson et al., 2000; Natacci et al., 2008] and in thanatophoric dysplasia [Hyland et al., 2003], and for HRAS mutations in Costello syndrome [Gripp et al., 2006; Sol-Church et al., 2009].