Amyloidosis is a group of rare conditions caused by the build-up of abnormal amyloid protein in organs and tissues throughout the body. Some forms of amyloidosis are hereditary. A new treatment, the first of its kind to be approved by the European Medicines Agency (EMA), will soon be available on the NHS in England and Scotland to treat a form of hereditary amyloidosis (hereditary transthyretin-related amyloidosis). This is exciting for the field of ataxia research, as it represents a breakthrough in the treatment of genetic conditions. Patisiran, the new amyloidosis treatment, works by a mechanism known as RNA interference.

Found in all cells, DNA contains instructions for how to make proteins. However, DNA is held inside the nucleus of the cell, whilst the machinery for making proteins is outside of the nucleus. Therefore, DNA instructions must be carried as a message, out of the nucleus, to where they can be accessed by the protein-making machinery. This message is called RNA.

Short interfering RNA (or siRNA), binds to a specific RNA message, and instructs the cell to destroy the message. This process is what is known as RNA interference. Patisiran is a siRNA which specifically binds to the amyloid protein message, thus preventing the abnormal amyloid protein from being produced.

siRNAs can only target one specific RNA message. Therefore, Patisiran will only be effective at treating this form of hereditary amyloidosis. The RNAi method has also been tested in early stage laboratory-based research for SCA1, SCA3 and SCA7, and was able to successfully reduce the production of the proteins that cause these ataxias.

The approval of Patisiran is a promising step forward because it gives us hope that similar siRNAs could be designed to target genes that cause hereditary ataxia.

Posted on 18/07/19