Microvillous inclusion disease

Microvillus inclusion disease, also known as Davidson's 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.

Prognosis
It is nearly always fatal unless, like short bowel syndrome patients, treated with parenteral nutrition or an intestinal transplant. The patient is often classified as being in "intestinal failure" and treated with the cohort of patients known as "short bowel syndrome" patients.

Pathophysiology
It is caused by a congenital lack of apical microvilli in the epithelial cells of the small intestine.

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

Genetic prevalence


Microvillus inclusion disease is thought to be extremely rare; only approximately 200 cases have been identified in children in Europe.

One patient, a teenage female living in Arizona, suddenly began to grow microvilli after thirteen years of TPN (Total Parenteral Nutrition) and Lipid dependency. She now enjoys a typical teenage diet and is seen regularly by her Gastroenterologist.

One patient from the UK was documented to achieve nutritional independence at age 3.

On 26 June 2009 a six year old girl diagnosed with microvillus inclusion disease became the third person in the UK to die of swine flu.

History
Microvillus inclusion disease was first described in 1978 by Davidson et al. It was originally described as familial enteropathy.