Gene mutation that 'blocks' pain identified

Scientists have identified a gene mutation that keeps people from feeling physical pain, a discovery that may lead to the development of new painkillers.
Congenital analgesia is a rare condition in which people do not sense physical pain coming in from outside stimuli.
Scientists at Jena University Hospital in Germany compared the gene sequence of a girl with the disorder against those of her parents, and identified a mutation in a gene called SCN11A.
This gene controls the development of channels on pain-sensing neurons. Sodium ions travel through these channels, creating electrical nerve impulses that are sent to the brain, which registers pain, 'New Scientist' reported.

Overactivity in the mutated version of SCN11A prevents the build-up of the charge that the neurons need to transmit an electrical impulse, numbing the body to pain.
"The outcome is blocked transmission of pain signals," said researcher Ingo Kurth.

In mice studies, researchers inserted a mutated version of SCN11A into the creatures and tested their ability to perceive pain.
They found that 11 per cent of the mice with the modified gene developed injuries similar to those seen in people with congenital analgesia, such as bone fractures and skin wounds.
The control group of mice with the normal SCN11A gene, did not develop such injuries, researchers said.

The altered mice also took 2.5 times longer on average than the control group to react to the "tail flick" pain test, which measures how long it takes for mice to flick their tails when exposed to a hot light beam.
The team is now searching for drugs that block the SCN11A channel.
"It would require drugs that selectively block this but not other sodium channels, which is far from simple," said Kurth.