…Is a very rare disease that is passed on through families as a genetic disorder. TTR-FAP is inherited, but not necessarily by all the children of an affected person – on average, only half of the children of an affected parent will inherit the gene for the disease. Even when the problem genes are passed on, those family members who inherit them may never develop the TTR-FAP disease, and stay free from it for their entire lifetime. Those family members who do develop the disease may experience the symptoms at almost any time, from being a young adult to sometimes quite late in life.

More than 100 different types of genetic mutations have been identified from all over the world in people with TTR-FAP, and large clusters of the disease occur in particular places. For example, there are hundreds of people with one particular genetic cause of TTR-FAP (called V30M) in Portugal, Sweden and Japan. This is in contrast to what we see in the UK where the current number of people who have been diagnosed with this type of inherited TTR-FAP is less than 100.

The typical symptoms that occur in TTR-FAP develop due to the abnormal gene causing the deposition of a substance called amyloid. When this happens, amyloid is deposited in tissues and organs throughout the body. TTR-FAP mainly affects the nervous system, causing abnormal and reduced sensation to touch and temperature in the early stages. The symptoms of TTR-FAP will usually escalate over time and this will lead to muscle weakness in the limbs and problems with other nerves that control body functions such as blood pressure and the bladder, as well as digestive functions. Most of the genetic mutations involved in amyloidosis are linked to amyloid being deposited in heart muscle (although less so with the V30M type mentioned above). TTR-FAP can also affect the jelly of the eye and sometimes other vital organs.

Diagnosis of TTR-FAP usually requires a range of tests; particularly taking small samples of tissue for examination (known as a biopsy) and genetic tests which can identify the mutated genes known to cause the disease. As TTR-FAP usually gets worse over time, an early diagnosis of the disease (as soon as the symptoms start to appear) is very important in order for people to receive the best medical care as soon as possible.

Once TTR-FAP has been diagnosed there are many ways in which symptoms can be eased, for example by medicines that reduce nerve pain and digestive symptoms. The disease usually progresses and typically leads to death within 5–15 years.

One of the effective treatments for TTR-FAP is liver transplantation. This is because the liver produces the abnormal protein that directly leads to the formation of amyloid deposits. If a person with TTR-FAP is able to have a liver transplant, the source of the disease is removed. Transplantation has been most successful in younger people with the V30M type of mutation – particularly when performed soon after the first symptoms have developed.

There is also optimism that new and effective treatments will become available in the UK during the next few years. There are at least five medicines currently in development. Encouragingly, the first of these new drugs is expected to become available in the near future.