Twelve publications have detailed individuals with, generally deleterious, pathogenic variants in TRAPPC9 that lead to a syndrome with severe intellectual disability, microcephaly, magnetic resonance imaging abnormalities, and in a majority of patients, dysmorphic facial features (Abbasi et al., 2017; Abou Jamra et al., 2011; Duerinckx et al., 2018; Giorgio et al., 2016; Hnoonual, Graidist, Kritsaneepaiboon, & Limprasert, 2019; Kakar et al., 2012; Koifman et al., 2010; Mir et al., 2009; Mochida et al., 2009; Mortreux et al., 2018; Najmabadi et al., 2007; Philippe et al., 2009). This evidence concerns the gene TRAPPC9 and microcephaly.