Microvillus inclusion disease, previously known as Davidsons disease, congenital microvillus atrophy and, less specifically, microvillus atrophy (note: microvillus is often misspelled as microvillous), is a rare genetic disorder of the small intestine that is inherited in an autosomal recessive pattern. Presentation
It is characterized by chronic, intractable diarrhea in new-born infants, starting in the first few days of life. This results in metabolic acidosis and severe dehydration. Pregnancy and birth are usually normal. Pathophysiology
It is caused by a congenital villus atrophy, atrophy of apical microvilli and intracellular accumulation of apical enzymes and transporters in the epithelial cells of the small intestine. MVID is in ost cases caused by mutations in the MYO5B gene. A minority of cases involves mutations in the STX3 gene. Diagnosis
Prenatal screening in utero is currently offered by several medical centers since the gene(s) involved in the disease were recently discovered to be MYO5B; Diagnosis is typically made by biopsy of the small intestine. Biopsy
The appearance of microvillous inclusion disease on light microscopy is similar to celiac sprue; however, it usually lacks the intraepithelial lymphocytic infiltration characteristic of celiac sprue and stains positive for carcinoembryonic antigen (CEA). The definitive diagnosis is dependent on electron microscopy. Differential diagnosis
The differential diagnosis of chronic and intractable diarrhea is:
Intestinal epithelial dysplasia
Syndromatic diarrhea
Immunoinflammatory enteropathy

Prognosis
It is nearly always fatal unless, like short bowel syndrome patients, treated with parenteral nutrition or an intestinal transplant.
Fibrosing colonopathy is a disease that arises in people with cystic fibrosis treated with high doses of pancreatic enzyme supplements. Symptoms are non-specific with abdominal pain, abdominal swelling, vomiting, and constipation.Risk factors include being young, prior surgery of the intestines, and the use of certain medications including corticosteroids and H2 blockers. It may appear similar to distal intestinal obstruction syndrome or inflammatory colitis such as Crohns disease.A maximum dose of 10,000 IU of lipase per kilogram per day is recommended for pancreatic enzyme supplementation to prevent this condition. More than 60 cases have been described as of 1999. The disease was suggested to be caused by methacrylic acid copolymer which is used as coating for delayed release of enzymes but there is no reliable evidence for that. == References ==