These newly uncovered functions for Treacle-Plk1 mechanistically account for the neurogenesis defects observed during brain development in Tcof1+/− mice and are particularly relevant for individuals with Treacher Collins syndrome as brain and behaviour anomalies such as microcephaly and mental retardation have been reported as part of the condition [43], [44], [45]. The gene discussed is PLK1; the disease is Treacher-Collins syndrome.