All males that carried the variant in HDAC8 showed microcephaly and distinct focal deformation of the skull.39 HDAC8 itself has been described to be regulated by SOX4,40 a transcription factor of the SOX family, which is required for B-lymphocyte development,41 and also during development of the sympathetic nervous system.42, 43. Here, SOX4 is linked to microcephaly.