Hereditary ATTR (hATTR) amyloidosis is a rare, genetic condition that affects an estimated 50,000 people worldwide. hATTR amyloidosis is caused by a gene change, or mutation, that affects the function of a protein called transthyretin (TTR). In hATTR amyloidosis, the TTR gene mutation causes the protein to take on an abnormal shape and misfold, which causes the protein to build up in various parts of the body, including the nerves, heart, and digestive system. This build-up of proteins, also called amyloid deposits, can cause a range of symptoms from polyneuropathy – numbness, tingling, and burning pain in hands and feet – to cardiomyopathy – dizziness, shortness of breath, and leg swelling – as well as gastrointestinal manifestations, such as diarrhea, nausea, and vomiting. This is not a complete list of symptoms that may be experienced in patients with hATTR amyloidosis. Each patient has a different experience and you may not experience all of these symptoms, or you may not experience them at the same time.
Northern Portugal has the largest cluster worldwide of individuals living with hATTR amyloidosis. Nearly 1 in every 1000 Portuguese originating from Póvoa de Varzim and Vila do Conde may be affected by the disease. Nationwide, approximately 1 in every 4,000 people in Portugal may be affected by hATTR amyloidosis, putting Americans of Portuguese descent at a higher risk for this hereditary disease. People of Portuguese descent experience earlier onset symptoms, with 87% experiencing symptoms before age 40. There are 120 or more gene mutations known to be associated with hATTR amyloidosis. Individuals of Portuguese descent have a high prevalence of the V30M mutation, which is the most common mutation associated with polyneuropathy symptoms of numbness, tingling, and burning pain in hands and feet.
As a hereditary disease, hATTR amyloidosis is passed down through family members. If one parent has hATTR amyloidosis, each child will have a 50% chance of inheriting the mutation from the parent. However, inheriting the mutation does not necessarily mean that they will develop the condition. Despite this family connection, hATTR amyloidosis is often misdiagnosed because its symptoms resemble those of other conditions and can vary widely among people with the same mutation.
Educating yourself and your loved ones about the symptoms of this condition can help you identify them if they occur. Symptoms may worsen over time, so it’s important to talk to your doctor to determine the right plan of action. This may include referring you to a doctor with more experience with hATTR amyloidosis or recommending you work with a genetic counselor. A genetic counselor can help you learn more about the genetic testing process and if a genetic test may be right for you.
If you think you or someone you know may be at risk for hATTR amyloidosis, it’s important to learn more. You can access educational resources and information at Alnylam Pharmaceuticals’ website www.hATTRbridge.com. In addition, you can request to speak with an Alnylam Patient Education Liaison (PEL) who can answer questions you may have about hATTR amyloidosis at www.hATTRPEL.com.
Please note that a discussion with a PEL should not take the place of any discussions you may have with your doctor. If you experience symptoms or become aware of a family history of the disease, speak to your doctor to find out the right action plan. Your doctor may refer you to a physician experienced in managing the disease or to a genetic counselor.
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