ZFHX4 and language disorder: Two of the nine variants were in genes previously associated with speech and/or language disorders - ROBO2, and ZFHX4; however, one of these was inherited from an unaffected parent (ROBO2, Proband 52), and for the other, it was not possible to determine whether the variant was de novo, as parental DNA was unavailable (ZFHX4, proband 43).