FGF4 and chondrodysplasia: Examples of such variants include the brachycephaly associated SMOC2 and BMP3 variants and chondrodysplasia-associated FGF4 retrogenes on chromosomes 12 and 18 (Parker et al. 2009; Schoenebeck et al. 2012; Marchant et al. 2017; Brown et al. 2017), and there are likely more, yet undiscovered variants.