Additional studies of MVID patient biopsies have revealed the aberrant localization of the apical proteins SI, sodium-hydrogen exchanger 2 (NHE2), NHE3, alkaline phosphatase (ALP), CFTR, dipeptidyl peptidase IV (DPP-IV), sodium-glucose linked transporter 1 (SGLT1) and phosphoinositide-dependent protein kinase 1 (PDK1) (Ameen and Salas, 2000; Dhekne et al., 2014; Kravtsov et al., 2014; Michail et al., 1998; Müller et al., 2008; Vogel et al., 2017a). The gene discussed is DPP4; the disease is microvillus inclusion disease.