STXBP2 and microvillus inclusion disease: MVID is autosomal recessively inherited with locus heterogeneity, where the majority of patients harbors biallelic mutations in the myosin 5b gene (MYO5B), and defects in syntaxin 3 (STX3) and syntaxin binding protein 2 (STXBP2) account for additional cases of MVID [1,5,6,7,8].