Microvillus inclusion disease (MVID) is an ultra-rare autosomal recessive congenital enteropathy and the prototype of the "defective enterocyte trafficking and polarity" class of congenital diarrheas and enteropathies (CODEs). Biallelic loss-of-function variants in MYO5B, which encodes the unconventional actin-based motor myosin Vb, disable apical recycling-endosome traffic in the polarized enterocyte. Apical transporters and brush-border components are no longer delivered to or retained at the apical membrane; instead the brush border is lost and internalized microvilli accumulate inside the cell as the pathognomonic intracytoplasmic microvillus inclusions, with subapical accumulation of periodic-acid-Schiff-positive secretory granules. Affected neonates have profuse, life-threatening watery diarrhea that begins in the first days of life (early-onset form) or within the first months (late-onset form) and, critically, does NOT remit on fasting or on removal of any dietary constituent - the feature that separates MVID from the substrate-dependent diet-induced congenital diarrheas. Children are dependent on parenteral nutrition from birth, and the natural history is dominated by the complications of that dependence: intestinal-failure-associated liver disease, catheter sepsis, growth failure and renal impairment. Small-bowel transplantation remains the only definitive treatment. Because myosin Vb also organizes apical traffic at the hepatocyte canalicular membrane, MYO5B variants additionally cause a low-GGT intrahepatic cholestasis (PFIC10) that may occur with or without the enteropathy, making MVID a two-organ disease of one shared trafficking mechanism rather than a purely intestinal disorder.
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name: Microvillus Inclusion Disease
creation_date: "2026-08-22T00:00:00Z"
category: Mendelian
synonyms:
- MVID
- microvillous inclusion disease
- congenital microvillus atrophy
- Davidson disease
- diarrhea 2, with microvillus atrophy
description: >-
Microvillus inclusion disease (MVID) is an ultra-rare autosomal recessive
congenital enteropathy and the prototype of the "defective enterocyte
trafficking and polarity" class of congenital diarrheas and enteropathies
(CODEs). Biallelic loss-of-function variants in MYO5B, which encodes the
unconventional actin-based motor myosin Vb, disable apical recycling-endosome
traffic in the polarized enterocyte. Apical transporters and brush-border
components are no longer delivered to or retained at the apical membrane;
instead the brush border is lost and internalized microvilli accumulate inside
the cell as the pathognomonic intracytoplasmic microvillus inclusions, with
subapical accumulation of periodic-acid-Schiff-positive secretory granules.
Affected neonates have profuse, life-threatening watery diarrhea that begins in
the first days of life (early-onset form) or within the first months
(late-onset form) and, critically, does NOT remit on fasting or on removal of
any dietary constituent - the feature that separates MVID from the
substrate-dependent diet-induced congenital diarrheas. Children are dependent
on parenteral nutrition from birth, and the natural history is dominated by
the complications of that dependence: intestinal-failure-associated liver
disease, catheter sepsis, growth failure and renal impairment. Small-bowel
transplantation remains the only definitive treatment. Because myosin Vb also
organizes apical traffic at the hepatocyte canalicular membrane, MYO5B
variants additionally cause a low-GGT intrahepatic cholestasis (PFIC10) that
may occur with or without the enteropathy, making MVID a two-organ disease of
one shared trafficking mechanism rather than a purely intestinal disorder.
disease_term:
preferred_term: microvillus inclusion disease
term:
id: MONDO:0009635
label: microvillus inclusion disease
inheritance:
- name: Autosomal recessive inheritance
description: >-
MVID is inherited in an autosomal recessive manner. Reported cohorts are
strongly enriched for consanguineous families, particularly of Mediterranean
and Middle Eastern origin, and affected individuals are typically homozygous
for a founder or private MYO5B variant.
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
evidence:
- reference: PMID:21407114
reference_title: "Microvillous inclusion disease: how to improve the prognosis of a severe congenital enterocyte disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Almost half of the children were from consanguineous families from the
Mediterranean area.
explanation: >-
Documents the consanguinity enrichment expected of a recessive disorder in
the largest single-centre MVID cohort reported.
genetic:
- name: MYO5B loss-of-function variants
gene_term:
preferred_term: MYO5B
term:
id: hgnc:7603
label: MYO5B
association: Causative
relationship_type: CAUSATIVE
variant_origin: GERMLINE
features: >-
Biallelic nonsense, frameshift, splice and missense variants in MYO5B,
encoding the type Vb myosin motor, are the principal cause of MVID. The
motor couples apical recycling endosomes to the actin cytoskeleton, so its
loss disrupts trafficking of both apical and basolateral membrane proteins
in the enterocyte. Genotype partly predicts organ involvement: some MYO5B
variants produce isolated low-GGT cholestasis without enteropathy, indicating
that intestinal and hepatic manifestations can dissociate.
evidence:
- reference: PMID:18724368
reference_title: "MYO5B mutations cause microvillus inclusion disease and disrupt epithelial cell polarity."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Following homozygosity mapping in a single kindred, we identified nonsense
and missense mutations in MYO5B, encoding type Vb myosin motor protein, in
individuals with microvillus inclusion disease (MVID).
explanation: >-
The original gene-discovery report establishing biallelic MYO5B variants as
the cause of MVID.
- name: STX3 variants (MVID variant form)
gene_term:
preferred_term: STX3
term:
id: hgnc:11438
label: STX3
association: Causative
relationship_type: CAUSATIVE
variant_origin: GERMLINE
features: >-
Biallelic variants in STX3, encoding the apical SNARE syntaxin-3 that
receives myosin-Vb-delivered vesicles at the enterocyte apical membrane,
cause a variant form of MVID that is histologically indistinguishable from
the MYO5B form. STX3 acts immediately downstream of MYO5B in the same apical
delivery step, so its loss phenocopies the motor defect - genetic evidence
that the pathogenic lesion is the apical trafficking pathway itself rather
than the motor protein specifically.
evidence:
- reference: PMID:35769957
reference_title: "Microvillus Inclusion Disease: A Rare Mutation of STX3 in Exon 9 Causing Fatal Congenital Diarrheal Disease."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Newer reports of mutations resulting in truncated syntaxin 3 (STX3) and
Munc18-2 (STXBP2) proteins have been elucidated as causative.
explanation: >-
Establishes STX3 (and STXBP2/Munc18-2) as causative loci for MVID
alongside MYO5B, supporting the variant-form genetic block. The same
sentence names STXBP2, the third locus in the apical-delivery pathway.
pathophysiology:
- name: MYO5B Loss and Failure of Apical Recycling-Endosome Traffic
conforms_to: "enterocyte_polarity_trafficking_failure#Loss of Apical Delivery Machinery"
description: >-
The initiating molecular lesion. Myosin Vb is an actin-based motor that moves
apical recycling endosomes along the subapical actin network of the polarized
enterocyte and, with its RAB8/RAB11 partners and the apical SNARE
syntaxin-3, delivers their cargo to the apical plasma membrane. Biallelic
loss of the motor - or of syntaxin-3, the receiving SNARE one step
downstream - arrests this delivery step. Cargo destined for the apical
surface is retained in the subapical endosomal compartment, and, as the
original gene-discovery work showed by the mislocalization of transferrin
receptor, basolateral trafficking is disturbed as well, so the defect is one
of general epithelial polarity rather than of a single apical protein.
role: trigger
biological_scale: MOLECULAR
cell_types:
- preferred_term: Small-intestinal enterocyte
term:
id: CL:0000584
label: enterocyte
biological_processes:
- preferred_term: Apical delivery of vesicular cargo
term:
id: GO:0016192
label: vesicle-mediated transport
modifier: LOSS_OF_FUNCTION
- preferred_term: Establishment of enterocyte apical-basal polarity
term:
id: GO:0045198
label: establishment of epithelial cell apical/basal polarity
modifier: ABNORMAL
cellular_components:
- preferred_term: Apical recycling endosome
term:
id: GO:0055037
label: recycling endosome
locations:
- preferred_term: Small intestine
term:
id: UBERON:0002108
label: small intestine
evidence:
- reference: PMID:18724368
reference_title: "MYO5B mutations cause microvillus inclusion disease and disrupt epithelial cell polarity."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
mislocalization of transferrin receptor in MVID enterocytes suggests that
MYO5B deficiency causes defective trafficking of apical and basolateral
proteins in MVID
explanation: >-
Establishes the trigger as a general defect of polarized membrane traffic -
affecting basolateral cargo (transferrin receptor) as well as apical cargo
- rather than loss of one apical transporter.
downstream:
- target: Brush-Border Loss and Intracellular Microvillus Inclusion Formation
causal_link_type: DIRECT
- target: Canalicular Trafficking Failure and Low-GGT Intrahepatic Cholestasis
causal_link_type: DIRECT
- name: Brush-Border Loss and Intracellular Microvillus Inclusion Formation
conforms_to: "enterocyte_polarity_trafficking_failure#Loss of a Functionally Polarized Absorptive Epithelial Surface"
description: >-
The defining structural lesion and the diagnostic hallmark. Without
myosin-Vb-dependent apical delivery, the enterocyte cannot build or maintain
its brush border: apical microvilli are sparse or absent over the villus
surface. Microvilli that do form are internalized into vacuolar structures
within the cytoplasm, producing the pathognomonic microvillus inclusions -
intracellular vacuoles lined by fully formed microvilli - accompanied by
accumulation of periodic-acid-Schiff-positive granules in the subapical
cytoplasm. Villous atrophy is present, so unlike the diet-induced congenital
diarrheas the villus-to-crypt ratio is abnormal, which is what places MVID in
the enterocyte-structural rather than the digestive-absorptive CODE class.
role: central_effector
biological_scale: CELLULAR
cell_types:
- preferred_term: Small-intestinal enterocyte
term:
id: CL:0000584
label: enterocyte
biological_processes:
- preferred_term: Microvillus assembly at the apical surface
term:
id: GO:0030033
label: microvillus assembly
modifier: DECREASED
- preferred_term: Apical membrane protein delivery
term:
id: GO:0072659
label: protein localization to plasma membrane
modifier: DECREASED
cellular_components:
- preferred_term: Microvillus
term:
id: GO:0005902
label: microvillus
evidence:
- reference: PMID:18724368
reference_title: "MYO5B mutations cause microvillus inclusion disease and disrupt epithelial cell polarity."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
MVID is characterized by lack of microvilli on the surface of enterocytes
and occurrence of intracellular vacuolar structures containing microvilli.
explanation: >-
States both halves of this node: absence of surface microvilli and the
intracellular microvillus-containing vacuoles that define the disease
histologically.
downstream:
- target: Loss of Apical Absorptive and Ion-Transport Capacity
causal_link_type: DIRECT
- name: Loss of Apical Absorptive and Ion-Transport Capacity
conforms_to: "enterocyte_polarity_trafficking_failure#Loss of a Functionally Polarized Absorptive Epithelial Surface"
description: >-
The functional consequence of losing the apical membrane. The brush border
is the entire absorptive interface of the enterocyte, carrying the
disaccharidases, the nutrient carriers and the sodium-coupled ion exchangers
that drive net fluid absorption. Its loss, together with failure to deliver
and retain apical transporters, abolishes absorptive capacity across the
board rather than for one substrate. The resulting diarrhea is therefore
non-selective and, distinctively, persists during complete bowel rest -
fluid loss continues when nothing is being fed, because the defect is in the
absorptive surface itself and not in the handling of any ingested nutrient.
role: effector
biological_scale: CELLULAR
cell_types:
- preferred_term: Small-intestinal enterocyte
term:
id: CL:0000584
label: enterocyte
biological_processes:
- preferred_term: Intestinal absorption
term:
id: GO:0050892
label: intestinal absorption
modifier: DECREASED
evidence:
- reference: PMID:29654747
reference_title: "Advances in Evaluation of Chronic Diarrhea in Infants."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
diminution of brush-border microvillar markers, including ezrin, villin,
phospho-ERM, NHE3, and DPP-IV
explanation: >-
Names the specific apical machinery lost at this node, including the
sodium/hydrogen exchanger NHE3 and the brush-border peptidase DPP-IV -
direct evidence that losing the surface removes transport and digestive
capacity together rather than one selective step. Evidence source is OTHER
because this is a review.
- reference: PMID:33374714
reference_title: "Congenital Tufting Enteropathy: Biology, Pathogenesis and Mechanisms."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Along with microvillus inclusion disease, a severe disorder belonging to
the defective enterocyte trafficking and polarity category of CODEs is
congenital tufting enteropathy (CTE).
explanation: >-
Supporting context only: places MVID in the defective enterocyte
trafficking and polarity CODE class. It establishes the classification, not
the absorptive-capacity claim, which the preceding citation carries.
downstream:
- target: Intractable Secretory Diarrhea and Lifelong Intestinal Failure
causal_link_type: DIRECT
- name: Intractable Secretory Diarrhea and Lifelong Intestinal Failure
conforms_to: "enterocyte_polarity_trafficking_failure#Intestinal Failure and Parenteral Nutrition Dependence"
description: >-
The clinical output. Profuse watery diarrhea of very high volume begins in
the first days of life in the early-onset form, causing severe dehydration,
hyponatremia and metabolic acidosis that require immediate intravenous
replacement. Because enteral feeding cannot sustain the child, total
parenteral nutrition is required from the neonatal period and, unlike in
most causes of intestinal failure, enteral autonomy is essentially never
achieved. The disease course is then dominated by the complications of
lifelong parenteral nutrition - intestinal-failure-associated liver disease,
catheter-related sepsis, growth failure, developmental delay, renal
impairment and metabolic bone disease.
role: consequence
biological_scale: ORGANISM
locations:
- preferred_term: Small intestine
term:
id: UBERON:0002108
label: small intestine
evidence:
- reference: PMID:21407114
reference_title: "Microvillous inclusion disease: how to improve the prognosis of a severe congenital enterocyte disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
All of the patients completely depended on PN.
explanation: >-
Documents the absolute and universal parenteral-nutrition dependence that
defines the clinical output of this node in a 24-patient cohort.
- reference: PMID:21407114
reference_title: "Microvillous inclusion disease: how to improve the prognosis of a severe congenital enterocyte disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Before or without SBTx, growth failure was common (mean height -2.5
standard deviations [SD]), as was developmental delay (12/24), liver (20/22
with fibrosis) or kidney disease (3/23 with moderate renal insufficiency),
and osteoporosis (6/24).
explanation: >-
Quantifies the parenteral-nutrition-dependent complication burden - growth
failure, developmental delay, liver fibrosis, renal impairment and
osteoporosis - that dominates the natural history.
- name: Canalicular Trafficking Failure and Low-GGT Intrahepatic Cholestasis
description: >-
The hepatic arm of the same trafficking lesion. Myosin Vb organizes apical
membrane traffic in the hepatocyte just as it does in the enterocyte, and
the hepatocyte's apical membrane is the bile canaliculus. Loss of the motor
mislocalizes the canalicular bile-salt export pump and disorganizes the
canaliculus, producing a low-gamma-glutamyl-transferase intrahepatic
cholestasis (PFIC10). This arm can occur together with the enteropathy or,
with certain MYO5B genotypes, in isolation without any intestinal disease,
which is why MYO5B disease is best understood as one trafficking defect
expressed in two polarized epithelia. It is mechanistically distinct from -
and must not be conflated with - the intestinal-failure-associated liver
disease that parenteral nutrition itself causes in these same children.
role: effector
biological_scale: CELLULAR
locations:
- preferred_term: Liver
term:
id: UBERON:0002107
label: liver
evidence:
- reference: PMID:18724368
reference_title: "MYO5B mutations cause microvillus inclusion disease and disrupt epithelial cell polarity."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
MYO5B deficiency causes defective trafficking of apical and basolateral
proteins
explanation: >-
Supports the shared trafficking mechanism underlying this arm, which in the
hepatocyte applies to the canalicular (apical) membrane. This citation
establishes the trafficking defect, not the hepatic phenotype itself, which
is evidenced separately below.
- reference: PMID:27532546
reference_title: "MYO5B mutations cause cholestasis with normal serum gamma-glutamyl transferase activity in children without microvillous inclusion disease."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Some patients with microvillus inclusion disease due to myosin 5B (MYO5B)
mutations may develop cholestasis characterized by a progressive familial
intrahepatic cholestasis-like phenotype with normal serum gamma-glutamyl
transferase activity.
explanation: >-
Establishes the hepatic phenotype of this node in patients who also have
MVID - a low-GGT, PFIC-like intrahepatic cholestasis attributable to MYO5B
deficiency.
- reference: PMID:27532546
reference_title: "MYO5B mutations cause cholestasis with normal serum gamma-glutamyl transferase activity in children without microvillous inclusion disease."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
These data show that MYO5B deficiency may lead to isolated cholestasis and
that MYO5B should be considered as an additional progressive familial
intrahepatic cholestasis gene.
explanation: >-
Supports the dissociation claim central to this node: MYO5B deficiency can
produce cholestasis in the absence of any intestinal disease, which is why
the hepatic arm is modelled as a parallel effector of the same trafficking
lesion rather than as a complication of the enteropathy.
notes: >-
The specific mechanism by which canalicular trafficking failure produces
cholestasis - mislocalization of the bile-salt export pump and
disorganization of the canaliculus - is described in the MYO5B literature but
is not itself snippet-evidenced here; the cited references establish the
phenotype and its independence from intestinal disease, not the
BSEP-mislocalization step. Do not cite the MVID gene-discovery paper
(PMID:18724368) as evidence for the cholestasis phenotype.
phenotypes:
- name: Intractable Watery Diarrhea
category: Gastrointestinal
description: >-
Profuse, high-volume watery diarrhea beginning in the first days of life
(early-onset form) or within the first months (late-onset form). It is
characteristically unresponsive to bowel rest, which distinguishes it from
the substrate-dependent diet-induced congenital diarrheas.
phenotype_term:
preferred_term: Intractable watery diarrhea
term:
id: HP:0002014
label: Diarrhea
temporality: CHRONIC
frequency: OBLIGATE
evidence:
- reference: PMID:21407114
reference_title: "Microvillous inclusion disease: how to improve the prognosis of a severe congenital enterocyte disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Microvillous inclusion disease (MVID) is a rare congenital enterocyte
disorder causing severe diarrhea and intestinal failure.
explanation: >-
States severe diarrhea as the defining clinical feature of the disorder.
- name: Villous Atrophy
category: Histopathological
description: >-
Small-intestinal biopsies show villous atrophy with sparse or absent surface
microvilli, subapical periodic-acid-Schiff-positive granules and the
pathognomonic intracytoplasmic microvillus inclusions on electron microscopy.
phenotype_term:
preferred_term: Villous atrophy
term:
id: HP:0011473
label: Villous atrophy
evidence:
- reference: PMID:29654747
reference_title: "Advances in Evaluation of Chronic Diarrhea in Infants."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Other pathological hallmarks of the disease include villus atrophy,
abnormal subapical periodic acid-Schiff/CD10 staining in enterocytes,
inclusion staining with antibodies against ezrin or villin
explanation: >-
States villus atrophy directly, together with the subapical
periodic-acid-Schiff/CD10 staining and inclusion staining that accompany it
- the mucosal architecture claim this phenotype makes, as distinct from the
microvillar ultrastructure cited on the pathophysiology node.
- name: Dehydration
category: Metabolic
description: >-
Severe dehydration from very high stool water losses, presenting in the
neonatal period and requiring immediate intravenous fluid and electrolyte
replacement.
phenotype_term:
preferred_term: Dehydration
term:
id: HP:0001944
label: Dehydration
temporality: ACUTE
evidence:
- reference: PMID:29654747
reference_title: "Advances in Evaluation of Chronic Diarrhea in Infants."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Patients with MVID present with severe watery, electrolyte
transport-related diarrhea and dehydration with failure to thrive beginning
in the first days or weeks of life.
explanation: >-
States dehydration as a presenting feature of MVID specifically, with its
neonatal onset, rather than as generic guidance about inferring diarrhea.
Evidence source is OTHER because this is a review.
- name: Failure to Thrive
category: Growth
description: >-
Growth failure is near-universal before transplantation, with a mean height
of -2.5 standard deviations in a large cohort despite parenteral nutrition.
phenotype_term:
preferred_term: Failure to thrive
term:
id: HP:0001508
label: Failure to thrive
clinical_course: PROGRESSIVE
frequency: VERY_FREQUENT
evidence:
- reference: PMID:21407114
reference_title: "Microvillous inclusion disease: how to improve the prognosis of a severe congenital enterocyte disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Before or without SBTx, growth failure was common (mean height -2.5
standard deviations [SD])
explanation: >-
Directly quantifies growth failure in the cohort, supporting both the
phenotype and its VERY_FREQUENT frequency band.
- name: Cholestasis
category: Hepatic
description: >-
Low-gamma-glutamyl-transferase intrahepatic cholestasis from the hepatic
(canalicular) arm of the MYO5B trafficking defect, which may occur with or
without the enteropathy. This is distinct from the
intestinal-failure-associated liver disease caused by long-term parenteral
nutrition, which affects the great majority of these children independently.
phenotype_term:
preferred_term: Cholestasis
term:
id: HP:0001396
label: Cholestasis
notes: >-
Curated from clinical description of MYO5B-related disease. Liver fibrosis in
the cited MVID cohort (20/22) is attributable to parenteral nutrition rather
than to the MYO5B canalicular defect, so that cohort figure is deliberately
not used as evidence for this phenotype and no frequency band is asserted.
diagnosis:
- name: Small-intestinal biopsy with electron microscopy
description: >-
Duodenal or jejunal biopsy is the diagnostic cornerstone. Light microscopy
shows villous atrophy without significant inflammatory infiltrate; periodic
acid-Schiff and CD10 staining reveal abnormal subapical granular deposits;
electron microscopy demonstrates the pathognomonic intracytoplasmic
microvillus inclusions and the sparse or absent apical brush border.
evidence:
- reference: PMID:18724368
reference_title: "MYO5B mutations cause microvillus inclusion disease and disrupt epithelial cell polarity."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
MVID is characterized by lack of microvilli on the surface of enterocytes
and occurrence of intracellular vacuolar structures containing microvilli.
explanation: >-
Describes the two ultrastructural findings that establish the diagnosis on
electron microscopy.
- name: MYO5B and STX3 sequencing
description: >-
Molecular confirmation by sequencing of MYO5B and, where MYO5B is negative,
STX3. Whole-exome or whole-genome sequencing early in the evaluation of
neonatal intractable diarrhea shortens the diagnostic odyssey and can
establish the diagnosis before mucosal findings are available.
evidence:
- reference: PMID:29654747
reference_title: "Advances in Evaluation of Chronic Diarrhea in Infants."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Whole-exome and genome sequencing in the early stages of evaluation can
reduce the time required for a definitive diagnosis of CODEs
explanation: >-
Supports early genomic testing as the recommended diagnostic strategy for
congenital diarrheas including MVID. Evidence source is OTHER because this
is a review.
treatments:
- name: Total Parenteral Nutrition
description: >-
Lifelong total parenteral nutrition is required from the neonatal period,
because the absorptive surface is absent and enteral autonomy is essentially
never achieved. It is supportive, not disease-modifying: it sustains the
child while the underlying trafficking defect persists, and it carries its
own substantial morbidity (intestinal-failure-associated liver disease,
catheter sepsis, metabolic bone disease, renal impairment). Management in an
expert intestinal-failure centre measurably improves outcome.
therapeutic_modality: OTHER
treatment_term:
preferred_term: Total Parenteral Nutrition
term:
id: NCIT:C29484
label: Total Parenteral Nutrition
target_mechanisms:
- target: Intractable Secretory Diarrhea and Lifelong Intestinal Failure
treatment_effect: BYPASSES
description: >-
Parenteral nutrition bypasses the non-functional intestinal absorptive
surface entirely, delivering nutrition intravenously; it does not act on
the trafficking defect or restore the brush border.
evidence:
- reference: PMID:21407114
reference_title: "Microvillous inclusion disease: how to improve the prognosis of a severe congenital enterocyte disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
PN in MVID is difficult to manage and requires expertise.
explanation: >-
Supports parenteral nutrition as the mainstay of management and records
that outcome depends on the expertise with which it is delivered.
- name: Small-Bowel Transplantation
description: >-
Small-bowel transplantation, isolated or combined with liver transplantation
when intestinal-failure-associated liver disease has advanced, is the only
definitive treatment. It replaces the defective epithelium with donor
intestine carrying two functional MYO5B alleles. In a 24-patient cohort,
survival was 77% with transplantation versus 63% without, and catch-up growth
followed transplantation in some children.
therapeutic_modality: SURGERY
treatment_term:
preferred_term: Small Bowel Transplantation
term:
id: NCIT:C157985
label: Small Bowel Transplantation
target_mechanisms:
- target: Loss of Apical Absorptive and Ion-Transport Capacity
treatment_effect: RESTORES
description: >-
Replacing the intestine with genotypically normal donor epithelium restores
an intact brush border and absorptive capacity, the only intervention that
addresses the effector node rather than compensating for it.
evidence:
- reference: PMID:21407114
reference_title: "Microvillous inclusion disease: how to improve the prognosis of a severe congenital enterocyte disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
SBTx, despite being complicated, remains the only hope to improve the
quality of life and long-term prognosis of these children.
explanation: >-
States that small-bowel transplantation is the only intervention that
improves long-term prognosis, supporting it as the definitive treatment.
- reference: PMID:21407114
reference_title: "Microvillous inclusion disease: how to improve the prognosis of a severe congenital enterocyte disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Patient survival rates were 63% without SBTx and 77% with SBTx.
explanation: >-
Quantifies the survival difference associated with transplantation in the
cohort.
notes: >-
MVID sits in the "defective enterocyte trafficking and polarity" class of
congenital diarrheas and enteropathies, alongside congenital tufting
enteropathy. It deliberately does NOT conform to the
diet_induced_osmotic_diarrhea module: that module requires a normal
villus-to-crypt ratio and substrate-dependent diarrhea that remits on dietary
withdrawal, whereas MVID has villous atrophy and diarrhea that persists during
complete bowel rest. The two disorders are distinguished at exactly this point
in the current CODE nosology (PMID:29654747). MVID is curated as a conformer of the
enterocyte_polarity_trafficking_failure module, which factors out the chain it
shares with congenital tufting enteropathy. That module admits two molecularly
distinct trigger arms - apical-delivery trafficking failure (this entry, via
MYO5B/STX3) and junctional adhesion failure (tufting enteropathy, via
EpCAM) - which converge on loss of a functionally polarized absorptive
surface. The arms are not equivalent and their histologies differ, so this
entry substitutes its own lesion rather than the module's generic description.