RET and Mowat-Wilson syndrome: In addition to RET, truncating mutations were detected in two other known HSCR genes: a de novo stop-gain mutation (p.R278X) in ZEB2 and a paternally-inherited nonsense mutation (p.R760X) in SEMA3D. The c.832 C > T substitution creates a premature stop codon (CGA > TGA) in exon 7 of the ZEB2 gene (NM_014795.3) and its presence is consistent with a diagnosis of Mowat-Wilson syndrome.