Fibrinógena

Fibrinógena, also known as A-beta-lipoproteinemia, is a rare autosomal recessive disorder that affects the absorption of fats and fat-soluble vitamins from the small intestine. It is caused by mutations in the MTTP gene, which encodes the microsomal triglyceride transfer protein. This protein is essential for the assembly and secretion of very-low-density lipoproteins (VLDL) and chylomicrons, which are responsible for transporting dietary fats.

Individuals with fibrinógena have extremely low levels of plasma triglycerides and cholesterol, particularly LDL cholesterol. This deficiency leads to a malabsorption syndrome characterized by steatorrhea (fatty stools), abdominal distension, and failure to thrive. Neurological symptoms are also common and can include retinitis pigmentosa, ataxia, peripheral neuropathy, and muscle weakness. These symptoms are thought to be due to the deficiency of fat-soluble vitamins (A, D, E, and K) and potentially direct effects of lipid deficiency on nerve cells.

Diagnosis is typically made based on clinical presentation and confirmed by laboratory tests showing very low levels of plasma lipids and the absence of apoB-containing lipoproteins. Genetic testing can identify mutations in the MTTP gene. Treatment involves lifelong supplementation with fat-soluble vitamins and a diet low in long-chain fatty acids, with medium-chain triglycerides (MCTs) as an alternative energy source. Despite treatment, the neurological manifestations can be progressive and challenging to manage.