Microvillous inclusion disease

Microvillous inclusion disease, also known as Davidson's disease, congenital microvillous atrophy and, less specifically, microvillous atrophy, 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
Diagnosis in utero is currently not possible as the gene(s) involved in the disease was only recently discovered to be MYO5B; diagnosis is 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


Microvillous inclusion disease is thought to be extremely rare; only, approximately, two dozen cases have been identified in the medical literature.

One patient, a teenage female living in Arizona, suddenly began to grow microvilli after thirteen years of TPN (Total Parenteral Nutrition) and Lipid dependancy. 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.

One patient from the Netherlands was documented to be sustained by enteral nutrition rather than parenteral nutrition, but did not appear to have any MYO5B mutations.

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

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