Rather mutations in GLI3 which result in a functional, repressive protein (Johnston et al., 2005), are linked to Pallister Hall Syndrome (PHS) an autosomal dominant disorder characterised by postaxial polydactyly, imperforate anus, hypothalamic hamartoma and hypopituitarism (Clarren et al., 1980; Hall et al., 1980). The gene discussed is GLI3; the disease is hypopituitarism.