NFATC4 and Brachycephaly: As NFAT proteins regulate the differentiation of both osteoblasts and osteoclasts (Aliprantis et al., 2008; Koga et al., 2005; Lee et al., 2009; Winslow et al., 2006) and mice deficient in NFATC2 and NFATC4 have brachycephaly and mid-facial hypoplasia (Arron et al., 2006), increased dosage of Dyrk1a in Dp1Tyb mice may be promoting the craniofacial defects by inhibiting NFAT function and hence perturbing osteogenesis.