Opitz G/BBB syndrome (OS) is a multiple congenital anomalies disorder characterized by malformations of the midline including hypertelorism, laryngo-tracheo-esophalgeal defects and hypospadias. There are two clinically indistinguishable genetic subtypes of Opitz G/BBB: X-linked Opitz G/BBB syndrome (XLOS), and autosomal dominant Opitz G/BBB syndrome (ADOS). The disease is Monarch Disease Ontology entry MONDO_0017138 (Opitz G/BBB syndrome). Also known as: Opitz G syndrome, Opitz GBBB syndrome, Opitz syndrome, Opitz-Frias syndrome, Opitz-GBBB syndrome, hypertelorism-oesophageal abnormality-hypospadias syndrome, hypospadias-dysphagia syndrome, hypospadias-hypertelorism syndrome.