Microvillous Inclusion Syndrome

Extremely rare inherited enteropathy that is typically apparent within hours or days after birth. The disorder is characterized by chronic, severe, watery diarrhea and malabsorption caused by hypoplasia and/or atrophy of the wall of the small intestine (e.g., hypoplastic villus atrophy, defective brush-border assembly and differentiation). In infants, chronic diarrhea and malabsorption may result in severe dehydration, electrolyte imbalance, malnutrition, failure to thrive, and acidosis.

Congenital Microvillous Atrophy; Davidson Disease.

Very rare but seems to be the most common cause of severe protracted diarrhea of neonatal onset in developed countries. In 1987, 30 cases were reported worldwide in a survey among centers specializing in pediatric gastroenterology. More recent reports indicate that typical congenital microvillous atrophy accounts for 80% of cases. In the Navajo reservation in Northern Arizona, the incidence is reported at 1:12,000 live births.

Probably an autosomal recessive trait.

It seems that the brush-border lesion is associated with a disorder of the enterocyte cytoskeleton; it results in failure of reabsorption of the large volumes of endogenous gastric, pancreatic, and biliary secretions.

History; absence of serosal (e.g., vasoactive intestinal peptide-secreting tumor, Zollinger-Ellison syndrome) or infectious (bacterial toxins) causes; fecal electrolyte concentrations similar to those seen in small intestinal fluid. Jejunal biopsies complete the diagnosis: on light microscopy, hypoplastic villus atrophy with abnormal brush-border pattern and positive staining material within the apical cytoplasm of enterocytes. On electronic microscopy, surface cells show absent or grossly abnormal microvilli with numerous vesicular bodies and characteristic microvillus inclusions; crypt cells appear normal but contain increased numbers of apical vesicles and vesicular bodies.

Infants develop severe secretory diarrhea within days of birth; more than 140 ml/kg body weight of feces can be produced every day. The disease is fatal without parenteral nutrition and even with such supplementation, most children die in infancy or early childhood. The only treatment is small bowel transplantation.

In infant or child on total parenteral nutrition (TPN), check hydration, levels of blood glucose and electrolytes, liver enzymes (TPN-associated cholestasis), and coagulation (vitamin K deficit). In patients at risk for thromboembolic complications (catheter-related sepsis, serum protein imbalance), ascertain patency of the great veins if a new central venous access has to be inserted. Patient may be on intravenous octreotide therapy. The presence of an altered gastrointestinal barrier increases the risk of systemic sepsis.

Blood glucose and electrolytes should be monitored intraoperatively on a regular basis. Patients on TPN must be maintained intraoperatively and serial measurements of electrolytes and glucose are needed.

No known implications.

Congenital Chloride Diarrhea: Caused by a defect in the Cl-/HCO3- exchangers in the brush-border membrane in the ileum and colon. Autosomal recessive inheritance. Higher incidence in Finland and the Middle East. Parenteral replacement of fluids and electrolytes during the neonatal period, but oral compensation can be achieved ...