TUBB2B and polymicrogyria: For instance, a E421K mutation in TUBB2B and a R262C mutation in TUBB3 both cause ocular motor dysfunction, whereas individuals with a T312M variant in TUBB2B and a R46G mutation in TUBB3 both present with multifocal polymicrogyria (Jaglin et al., 2009; Tischfield et al., 2010; Cederquist et al., 2012; Bahi-Buisson et al., 2014).