SLC9A3 and microvillus inclusion disease: Diarrhea in patients with MVID is associated with villus blunting, loss of microvilli on the apical membrane of enterocytes, the expansion of autophagic lysosomes, and loss of apical transporters, such as sodium/proton exchanger 3 (NHE3/SLC9A3), sodium-dependent glucose transporter 1 (SGLT1/SLC5A1), and peptide transporter 1 (PEPT1/SLC15A1) (6, 7).