Interestingly, individuals with mutations in either STX3 (Wiegerinck et al., 2014), which encodes the transmembrane protein syntaxin-3, or STXBP2 (Stepensky et al., 2013), which encodes Munc18-2, develop the clinical symptoms and cellular characteristics of MVID. Here, STXBP2 is linked to microvillus inclusion disease.