In 2014, Tsurusaki et al. first demonstrated that de novo variants in SOX11 can result in Coffin-siris syndrome 9 (CSS9, OMIM#615866) in two patients and animal models (Tsurusaki et al., 2014). Here, SOX11 is linked to intellectual developmental disorder with microcephaly and with or without ocular malformations or hypogonadotropic hypogonadism.