MYO5B and microvillus inclusion disease: MVID is caused by heterogenous mutations in myosin Vb (MYO5B) (Müller et al., 2008; van der Velde et al., 2013) or syntaxin 3 (STX3) genes (Wiegerinck et al., 2014), which both encode proteins that function in the intracellular trafficking and membrane fusion cell machinery.