Familial Amyloid Polyneuropathy (FAP) is a rare hereditary disorder that affects the peripheral nerves and causes the abnormal accumulation of amyloid protein deposits in different tissues of the body. Amyloid proteins are produced by the liver and are normally broken down and eliminated. However, in individuals with FAP, a mutation in the transthyretin (TTR) gene leads to the production of abnormal TTR protein, which forms insoluble amyloid fibrils that build up in different organs, particularly the nerves.
The deposition of amyloid fibrils in the peripheral nerves results in progressive and often debilitating damage to the nervous system, leading to a wide range of symptoms depending on the affected nerves. Common signs of FAP include sensory disturbances such as numbness, tingling, and pain in the limbs, as well as weakness, muscle wasting, and loss of reflexes. As the disease progresses, it can also affect other organs like the heart, kidneys, and gastrointestinal system, leading to heart failure, renal dysfunction, and digestive problems.
FAP is an autosomal dominant genetic disorder, meaning that an affected individual has a 50% chance of passing the mutated gene on to their children. The age of onset and severity of symptoms can vary widely among affected individuals, even within the same family. There are different types of FAP, depending on the specific mutation in the TTR gene and the associated clinical features.
Management of FAP focuses on symptom relief and slowing disease progression. Treatment options include liver transplantation, which replaces the liver's ability to produce mutant TTR protein, and medications that stabilize or reduce the production of amyloid fibrils. Ongoing research is being conducted to develop new therapies targeting the underlying causes of FAP.
