Microvillus inclusion disease

Microvillus inclusion disease (MVID), also known as microvillous atrophy or Davidson's disease, is a rare and severe inherited disorder of the intestinal epithelium that presents in the neonatal period with life-threatening, intractable watery diarrhea. The disease is caused by defects in the enterocytes (intestinal lining cells), where the microvilli — tiny finger-like projections on the cell surface responsible for nutrient absorption — are absent or severely reduced on the cell surface and instead are found abnormally located within intracellular inclusion bodies. MVID is primarily caused by mutations in the MYO5B gene, which encodes myosin Vb, a motor protein essential for intracellular trafficking and polarized recycling of apical membrane components. Less commonly, mutations in STX3 (syntaxin 3) have been identified in a variant form of the disease. The gastrointestinal system is the primary organ system affected. Affected infants typically develop profuse, secretory diarrhea within the first days to weeks of life (early-onset form), though a late-onset form presenting at approximately 2-3 months of age has also been described. The diarrhea persists even when oral feeding is completely stopped, leading to severe dehydration, metabolic acidosis, and failure to thrive. Diagnosis is confirmed by characteristic findings on intestinal biopsy, including periodic acid-Schiff (PAS)-positive intracellular inclusions, loss of brush border staining on light microscopy, and the pathognomonic microvillus inclusions seen on electron microscopy. CD10 immunostaining can also aid in diagnosis. There is currently no curative medical therapy for MVID. Affected children are dependent on total parenteral nutrition (TPN) for survival, which carries significant risks including liver disease (parenteral nutrition-associated liver disease), catheter-related infections, and thrombosis. Intestinal transplantation remains the only definitive treatment option and has been performed in a number of patients, though it carries substantial morbidity and mortality. The long-term prognosis remains guarded, and multidisciplinary management at specialized centers is essential for optimizing outcomes.

Common questions about Microvillus inclusion disease