Abetalipoproteinemia is a rare genetic disorder that affects the body's ability to absorb dietary fats, cholesterol, and fat-soluble vitamins. It is caused by mutations in the microsomal triglyceride transfer protein (MTTP) gene, which is responsible for the production of a protein called MTP. This protein plays a crucial role in the assembly and secretion of lipoproteins, which are responsible for transporting fats and fat-soluble vitamins in the bloodstream.
Individuals with abetalipoproteinemia have mutations in both copies of the MTTP gene, one inherited from each parent. This autosomal recessive inheritance pattern means that both parents must carry a copy of the mutated gene for their child to develop the disorder. If both parents are carriers, there is a 25% chance with each pregnancy that the child will inherit two copies of the mutated gene and develop abetalipoproteinemia.
The mutations in the MTTP gene result in the production of an abnormal or nonfunctional MTP protein. Without functional MTP, the body is unable to package fats and fat-soluble vitamins into lipoproteins called chylomicrons. Chylomicrons are essential for the absorption and transport of dietary fats from the intestines to various tissues throughout the body.
As a result of the impaired chylomicron formation, individuals with abetalipoproteinemia experience malabsorption of fats and fat-soluble vitamins. This leads to a range of symptoms and complications, including:
Early diagnosis of abetalipoproteinemia is crucial to prevent or manage complications. Genetic testing can confirm the presence of mutations in the MTTP gene, while blood tests can reveal low levels of cholesterol, triglycerides, and fat-soluble vitamins. Treatment typically involves a specialized diet that includes high doses of fat-soluble vitamins and medium-chain triglycerides, which are more easily absorbed by the body.
In conclusion, abetalipoproteinemia is caused by mutations in the MTTP gene, resulting in the production of a nonfunctional MTP protein. This leads to impaired chylomicron formation and subsequent malabsorption of fats and fat-soluble vitamins. The disorder is inherited in an autosomal recessive manner, requiring both parents to carry a copy of the mutated gene. Early diagnosis and appropriate management are essential to prevent complications and improve the quality of life for individuals with abetalipoproteinemia.