In addition, autosomal dominant mutations of NOTCH1, RBPJ, DLL4 and ARHGAP31 give rise to AOS (Aminkeng, 2015; Hassed et al., 2012; Meester et al., 2015; Southgate et al., 2015; Stittrich et al., 2014). Here, DLL4 is linked to Adams-Oliver syndrome.