What is amyloidosis?
Amyloidosis occurs when abnormal proteins called amyloids build up and form deposits. The deposits can collect in organs such as the kidney and heart. This can cause the organs to become stiff and unable to work the way they should.
There are six main types of amyloidosis:
- Primary (AL) – with no known cause
- Secondary (AA) – caused by another disease, including some types of cancer
- Familial (ATTR & non-ATTR) – passed down through genes
- Dialysis-related (DRA)
- Senile systemic (SSA or Wild-Type)
Symptoms can vary, depending upon which organs are affected. Treatment depends on the type of amyloidosis you have. The goal is to help with symptoms and limit the production of proteins. If another disease is the cause, it needs to be treated.
Hereditary ATTR Amyloidosis
What is hereditary ATTR amyloidosis?
Hereditary ATTR amyloidosis is a familial subtype of amyloidosis. Hereditary ATTR amyloidosis is an inherited genetic disease affecting the nervous system and the heart.
The genetic mutation that causes hereditary ATTR amyloidosis produces a protein that forms into an abnormal shape. These abnormal “misfolded” proteins can be deposited and cluster in the body’s nerves and organs, causing complications.
There are three categories of ATTR amyloidosis:
- Familial amyloid cardiomyopathy (FAC)
- Familial amyloid polyneuropathy (FAP)
- Senile systemic amyloidosis also knows as wild-type ATTR amyloidosis
What are the symptoms of hereditary ATTR amyloidosis?
For each patient, the symptoms will depend on which organs are affected by the protein deposits:
- Weight loss
- Progressive fatigue
- Shortness of breath
- Leg swelling
- Palpitations and abnormal heart rhythms (atrial fibrillation)
- Chest pains
- Peripheral neuropathy
- Sensorimotor impairment
- Autonomic neuropathy
- Diarrhea or constipation
- Bladder control issues
- Weight loss
- Loss of appetite or a feeling of fullness after eating small amounts
- Nephrotic syndrome (excess protein in the urine)
- Swelling of legs, belly, arms, and lungs
What causes hereditary ATTR amyloidosis?
Amyloidosis is caused by abnormal deposition and accumulation of proteins in the tissues of the body.
In ATTR amyloidosis, a protein called transthyretin (TTR) is the amyloid protein that forms the amyloid deposits, due to a genetic mutation in the TTR gene.
How is hereditary ATTR amyloidosis diagnosed?
The main diagnostic testing for any amyloidosis disease includes:
- Blood tests
- Urine tests
After amyloidosis is confirmed and it is determined that there is transthyretin amyloid protein present, the protein needs to be identified by protein sequence analysis and DNA sequencing to confirm the hereditary ATTR amyloidosis diagnosis.
What are the treatments for hereditary ATTR amyloidosis?
Two forms of treatment exist for hereditary ATTR amyloidosis: supportive and source. The former focuses on symptom management and improving quality of life, while the latter aims to fight the disease at its source. Source treatment options include a liver transplant, ONPATTRO, and TEGSEDI. Additionally, VYNDAQUEL and VYNDAMAX exist for the treatment of hereditary ATTR amyloidosis cardiomyopathy. Research is ongoing for more treatment options.