IQSEC2 and Intellectual disability: IQSEC2 is an X-linked gene which has been previously associated with intellectual disability (ID), autism and epilepsy (Shoubridge et al., 2010, 2019; Fieremans et al., 2015; Alexander-Bloch et al., 2016; Kalscheuer et al., 2016; Zerem et al., 2016; Mignot and Depienne, 2018) with mutations in IQSEC2 accounting for approximately 2% of patients with ID and epilepsy referred for exome sequencing (Heyne et al., 2018).