Gene silencing drugs spared patients from the crippling pain caused by porphyria, in a clinical trial.
Sue BurrellImage copyrightSue Burrell
Image caption Sue Burrell no longer has severe bouts of pain.

Doctors have used a new type of medicine called "gene silencing" to reverse a disease that leaves people in crippling pain.

The condition, acute intermittent porphyria, also causes paralysis and is fatal in some cases.

The novel approach fine-tunes the genetic instructions locked in our DNA.

Doctors say they are "genuinely surprised" how successful it is and that the same approach could be used in previously untreatable diseases.

How bad is porphyria?

Sue Burrell, from Norfolk, has endured pain few could imagine and needed to take strong opioid painkillers every day.