Rare illness that took his life caused by abnormal proteins

MARTIN McGuinness suffered from amyloidosis, a group of rare conditions caused by deposits of abnormal protein, amyloid, in tissues and organs throughout the body.

Usually proteins begin as a string of amino acids that fold into a 3D shape to perform useful functions within our cells – but in amyloids, the proteins have folded abnormally and clumped together.

There are about 30 different proteins that can misfold and form amyloid, and therefore there are many different types of the illness. The majority occur as rare complications of blood or inflammatory conditions, but up to 10% of cases are inherited. One hereditary form, ATTR amyloidosis, is an inherited genetic disease that affects the nervous system and the heart to varying degrees.

One variant of ATTR amyloidosis – known as ATTR T60A, or Thr60AIa – was first noted in an Irish family in 1986. A cluster of cases has since been identified in Co. Donegal, where up to 1% of the population is estimated to have the mutation. A 1995 study of the Donegal cases found that nearly all those affected were descended from a person with a common ancestral surname.

‘The original family with this name was descended from a man called Conall Gulban, after whom the county Donegal (previously known in Gaelic as Tír Chonall, meaning land of Conall) is named,’ the research reported.

Amyloid deposits can cause stiffening of the heart muscle, resulting in symptoms such as shortness of breath, weight loss, abnormal rhythms, fatigue and dizziness.

Patients with hereditary ATTR T60A amyloidosis can expect to survive for more than six years after the symptoms present, according to experts at the Royal Free Hospital in London.