Types of amyloidosis
TTR amyloidosis
Transthyretin is a protein made by the liver, whose job is to carry thyroid hormone through the blood. Everyone has it. In ATTR amyloidosis it loses its shape, aggregates into fibrils and settles in the tissues — above all in the heart. Two quite different things can set that off, and telling them apart is the first task.
01
One protein
Key idea
One protein, two diseases. Genetic testing is required to determine whether ATTR amyloidosis is hereditary or wild-type, and the result may also have implications for relatives.
A transport protein
Transthyretin — TTR for short — is produced by the liver and carries thyroid hormone around the body. It is an ordinary protein, and everyone carries it.
When it becomes unstable it changes shape, loses its solubility, and aggregates into amyloid fibrils that the body cannot break down. What makes it unstable is precisely what separates the two forms of the disease.
Where it settles
Chiefly in the heart, where deposits thicken and stiffen the ventricle walls until the chambers no longer fill properly. The nerves are frequently involved as well, especially in the hereditary form.
Carpal tunnel syndrome, often in both hands, commonly appears five to ten years before any heart symptom. It is the earliest thing this disease tends to say about itself.
02
Two routes to the same protein
Either the gene is normal and age destabilises the protein, or a mutation destabilises it from the outset. Everything else follows from that.
wtATTR
Wild-type — acquired with age
In wild-type ATTR amyloidosis, no disease-causing TTR variant is identified. Ageing is the main recognised risk factor. It is a disease of later life, dominated by the heart, and for a long time it was dismissed as the heart simply growing old.
It is not inherited, and nothing is passed to your children.
hATTR
Hereditary — carried in the gene
A mutation in the TTR gene, inherited from a parent, destabilises the protein from the start. It may strike the nerves, the heart, or both, and symptoms can appear at any point from early adulthood.
Because it runs in families, a diagnosis is never about one person alone.
In the heart, the two can look identical. Only a genetic test distinguishes them — which is why that test forms part of the diagnosis, and why its answer concerns your relatives and not only you.
This page is intended as general information for patients, families and healthcare professionals. It does not replace medical advice. Always discuss your situation with your own specialist team.