SF3B4 and dysostosis: By studying the heterozygous SF3b4 mutants, which are haploinsufficient (Bernier et al., 2012; Petit et al., 2014; Marques et al., 2016), it was determined that SF3b4 is a causative factor for NS, an acrofacial dysostosis that causes upper limb and facial-mandibular defects (Wieczorek, 2013).