DLL4 and Adams-Oliver syndrome: Interestingly, autosomal dominant forms of Adams-Oliver Syndrome (OMIM 614814, 616028, 616589) caused by germline loss-of-function mutations in RBPjk, NOTCH1, and the NOTCH ligand, DLL4, commonly present with abnormalities of the hands and feet including fused digits (syndactyly), severe shortening of digits (brachydactyly), and/or complete loss of digits (oligodactyly).