Clinical Spectrum, Genetic Profile, and Genotype–Phenotype Correlations in Microvillus Inclusion Disease: A Systematic Review

ABSTRACT Microvillus inclusion disease (MVID) is a rare congenital enteropathy caused by defects in intestinal epithelial apical trafficking and polarity. Although its genetic basis is well established, the clinical spectrum and genotype–phenotype correlations remain incompletely defined. We aimed to systematically characterize the clinical and genetic features of MVID and investigate genotype–phenotype correlations. A systematic review of MVID literature was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) statement, with database searches performed from inception to August 5, 2026. A total of 118 studies comprising 336 patients were included. Intractable diarrhea was reported in 98.8% (332/336). Extraintestinal involvement was documented in 243 patients and was most often hepatic (127/243, 52.3%), with cholestasis in 80/127 (63.0%), cirrhosis in 16/127 (12.6%), and hepatic failure in 8/127 (6.3%). Among 287 patients with treatment data, 280 (97.6%) received total parenteral nutrition (TPN). Management patterns changed across reporting eras, with intestinal transplantation reported in 33.3% (23/69) of patients in 1996–2010 and 12.9% (16/124) in 2011–2026. Pathogenic variants were identified most commonly in MYO5B , followed by STXBP2 , STX3 , and UNC45A . Bi‐allelic null MYO5B variants were associated with earlier onset than bi‐allelic non‐null variants ( p  MYO5B variant was associated with reduced liver‐intestine transplant‐free survival (log‐rank p  = 0.040). MVID is characterized by intractable diarrhea and substantial hepatic involvement. Molecular diagnosis clarifies the genetic etiology and provides a basis for genotype‐informed clinical stratification. Treatment strategies should be interpreted in an era‐specific context. Systematic Review Registration: PROSPERO (CRD42024503464).