Which are the causes of Microvillus Inclusion Disease?

Microvillus Inclusion Disease (MVID) is a rare genetic disorder that affects the functioning of the small intestine. It is characterized by severe diarrhea, malabsorption, and failure to thrive in affected infants. MVID is caused by mutations in specific genes that are involved in the development and maintenance of microvilli, which are tiny finger-like projections on the surface of intestinal cells.

Genetic mutations: The primary cause of MVID is genetic mutations in the MYO5B, STX3, or STX4 genes. These mutations disrupt the normal functioning of the microvilli, leading to the characteristic symptoms of the disease. MYO5B gene mutations are the most common cause of MVID, accounting for approximately 70% of cases. STX3 and STX4 gene mutations are less common but can also result in the development of MVID.

Impaired microvilli function: Microvilli play a crucial role in the absorption of nutrients from the intestine into the bloodstream. They increase the surface area of the intestinal lining, allowing for efficient absorption of nutrients. In MVID, the mutations in the MYO5B, STX3, or STX4 genes disrupt the formation and maintenance of microvilli, leading to a significant reduction in their number and functionality. This impairs the absorption of nutrients, resulting in chronic diarrhea and malnutrition.

Inherited or sporadic: MVID can be inherited in an autosomal recessive manner, meaning that both parents must carry a copy of the mutated gene for their child to develop the disease. In some cases, MVID can also occur sporadically, without a family history of the condition. Sporadic cases may result from de novo mutations, which occur spontaneously during the formation of reproductive cells or early embryonic development.

Other factors: While genetic mutations are the primary cause of MVID, other factors may influence the severity and progression of the disease. For example, certain variations in other genes involved in intestinal development and function may modify the effects of the primary mutations. Additionally, environmental factors and the presence of other medical conditions can also impact the clinical presentation of MVID.

Conclusion: Microvillus Inclusion Disease is primarily caused by genetic mutations in the MYO5B, STX3, or STX4 genes, which disrupt the formation and maintenance of microvilli in the small intestine. These mutations impair nutrient absorption, leading to severe diarrhea and malabsorption. MVID can be inherited or occur sporadically, and other factors may influence the severity of the disease. Early diagnosis and management are crucial for improving the outcomes and quality of life for individuals with MVID.