Pushkal Garg, MD, Chief Medical Officer at Alnylam discusses hereditary ATTR (hATTR) amyloidosis, a rare condition that affects an estimated 50,000 people worldwide. Symptoms can affect multiple parts of the body, including the nervous (nerve), cardiac (heart), and gastrointestinal (digestive) systems.
Amyloidosis refers to a group of conditions caused by the build-up of amyloid fibrils in the body. Each type is caused by a different misfolded protein. There are multiple types of amyloidosis, including amyloid A (AA) amyloidosis and amyloid light chain (AL) amyloidosis, which are the most common.
hATTR amyloidosis is caused by a gene change (mutation) that affects the function of a protein in the blood called transthyretin (TTR). This protein is made primarily in the liver. The symptoms of hATTR amyloidosis can vary widely among people with the same mutation and even within families, though some do see a pattern of symptoms develop. Different symptoms may appear at different times for each individual. The age that initial symptoms appear may vary, ranging from the mid-20s to the mid-60s.
hATTR amyloidosis affects several parts of the body, including:
- The peripheral nervous system, which is made up of nerves that branch out from the brain and spinal cord and communicate with the rest of the body including your arms and legs
- The cardiac system, which includes the heart and blood vessels, transports blood through veins and delivers oxygen to cells in the body
- The autonomic nervous system, which is made up of nerves that connect the brain and spinal cord to organs such as the heart, stomach, and intestines, and helps to control bodily functions such as breathing, digestion, and heart rate
There are therapies available that address the underlying cause of hATTR amyloidosis. These treatments can help by decreasing the amount of TTR protein that’s made in the body. Liver transplant is also an option for some patients who meet certain eligibility criteria. Due to the progressive nature of hereditary ATTR (hATTR) amyloidosis, managing symptoms is an ongoing process. Physicians may prescribe medications to treat some of these symptoms and reduce the daily impact they may have.
Onpattro (patisiran) treats the polyneuropathy caused by an illness called hereditary transthyretin-mediated amyloidosis and is indicated for adults only.