Gene mutation blocks pain

Research published in the journal Nature last week has pinpointed a mutated form of a gene which prevents carriers from feeling pain. It is hoped the research might offer potential new ways to treat severe pain.

The research, carried out by Dr Geoffrey Woods, from the Department of Medical Genetics and the University of Cambridge Institute for Medical Research (CIMR), was based on a group of related families in northern Pakistan in which several individuals seemed entirely unaffected by pain. All affected individuals were otherwise normal and were able to perceive a number of sensations such as touch and temperature. However, there were adverse consequences of their pain insensitivity. Carriers had suffered severe injuries throughout their lives as a result of being unable to detect pain, and therefore limit their actions accordingly. For example, several of the individuals had fractured bones without noticing.

The researchers compared DNA samples from six children and found they all share a mutation in the SCN9A gene, which is strongly expressed at the end of pain-sensing neurons. SCN9A encodes a sodium channel which is involved in allowing electrical charge to flow into nerve cells and trigger a signal. Normally when a painful stimulus is felt the channel amplifies it and excites the neuron, sending an electrical signal to the brain. The mutation discovered disrupts this process by making the sodium channel protein useless and consequently the brain is unable to receive pain signals.

Dr Woods said that 'this paper shows that rare diseases can still be of great importance, because of the insights they give into biological and developmental processes'. Dr John Wood, from University College London, said: 'The work of Geoff Woods and his team has provided us with an exciting new target for pain killing drugs - potentially this is as important as the identification of the morphine receptors'.