TWIST1 and Saethre-Chotzen syndrome: In addition, we show that the zebrafish homologs of the Saethre-Chotzen syndrome genes TWIST1 and TCF12 are selectively expressed in and required to establish the grem1a + MSM population, supporting roles of these transcription factors outside of osteogenic cells in regulating calvarial bone growth and suture maintanence5,10,13,35.