Microvillous inclusion disease

Microvillus inclusion disease, previously 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.^[1][2]

Microvillus inclusion disease
Other names	Davidson's disease
Microvillus inclusion disease has an autosomal recessive pattern of inheritance.

Presentation

It is characterized by chronic, intractable diarrhea in new-born infants, starting in the first few days of life.^[3] This results in metabolic acidosis and severe dehydration. Pregnancy and birth are usually normal.^{[citation needed]}

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.^[4] MVID is in most cases caused by mutations in the MYO5B gene. Other genes are also responsible of the disease: STXBP2 or Munc18-2 (also causing Familial Hemophagocytic Lymphohistiocytosis (FHL), STX3 and UNC45A.^{[citation needed][5]}

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;^[6][7] Diagnosis is typically made by biopsy of the small intestine.^[1]

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).^[2] The definitive diagnosis is dependent on electron microscopy.^[8]

Differential diagnosis

The differential diagnosis of chronic and intractable diarrhea is:^[9]

• 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.^[3] The patient is often classified as being in "intestinal failure" and treated with the cohort of patients known as "short bowel syndrome" patients.^{[citation needed]}

One patient from the UK was documented as achieving nutritional independence at age 3.^[10] On 26 June 2009, a six-year-old girl with microvillus inclusion disease became the third person in the UK to die of swine flu. This was attributed to her weakened immune system.^[11]

Prevalence

Microvillus inclusion disease is extremely rare, however, no prevalence data have been published. An estimate of a few hundred children with the disease in Europe has been made but no time frame to which this count applies is given. Countries with a higher degrees of consanguinity experience higher prevalence rates due to its autosomal recessive transmission.^[12]

History

Microvillus inclusion disease was first described in 1978 by Davidson et al.^[13] It was originally described as familial enteropathy.^{[citation needed]}