Given the high level of STX3 expression in the murine and non-mammalian retina and roles for Stx3 in protein trafficking in photoreceptors (Chuang et al. 2007; Kakakhel et al. 2020; Mazelova et al. 2009; Zulliger et al. 2015), and in neurotransmitter release at the first two synapses in the visual throughput pathway (Curtis et al. 2008, 2010; Datta et al. 2017; Liu et al. 2014) we asked whether MVID subjects with STX3 variants might have visual impairment. The gene discussed is STX3; the disease is microvillus inclusion disease.