Key points from article :
Gene silencing used to reverse porphyria - a disease that leaves patients in crippling pain.
People with porphyria have disruption to haem production - part of the blood oxygen transport system.
Rather than changing DNA (as in gene therapy) the treatment uses RNA interference.
This lowers the levels of an enzyme involved in haem production and prevents the build-up of toxic proteins.
The therapy cut the number of severe attacks by 74%.
Need to keep taking the treatment for the therapy to work.
Approach could be used in other previously untreatable diseases.
