TCOF1 and Treacher-Collins syndrome: The TCOF1 gene that is predominantly mutated in Treacher-Collins syndrome (TCS, OMIM: 154500) (Bowman et al., 2012) encodes a nucleolar phosphoprotein that has recently been proposed to function as a DNA damage response factor that regulates rDNA transcription by recruiting the Nijmegen breakage syndrome protein NBS1 to nucleoli following DNA damage (Ciccia et al., 2014, Larsen et al., 2014).