A mutation in one key gene can rob people of their ability to experience pain, a study in the 14 December 2006 issue of Nature (Vol. 444, No. 7121, pp. 894-898) suggests. It's thought the discovery could lead to the development of whole-body analgesics that do not cause side effects.
Although they are rare, people with the inability to feel pain do exist. Their peripheral and central nervous systems are apparently normal, and they usually enjoy good health aside from the risk of accidents and undetected illnesses. But the cause of this remarkable condition has been an enigma.
C. Geoffrey Woods and colleagues studied individuals from three related families from Northern Pakistan who had never experienced pain. Each carried a mutation in the SCN9A gene, which encodes a protein called a voltage-gated sodium channel. The protein is commonly found on pain-responsive neurons, and tissue culture studies reveal that the mutations stop the channel from functioning. This in turn seems to prevent the individuals from experiencing pain.
Pain is an essential sense that has evolved in all complex organisms to minimize tissue and cellular damage, and hence prolong life. The first person with pain-insensitivity that Woods' team investigated for the present study was a boy who was well known to the medical service because he regularly performed 'street theatre'. He could place knives through his arms and walk on burning coals, without experiencing any pain. He died on his fourteenth birthday, after jumping off a house roof. Woods and his team studied six related members from the boy's clan.
C. Geoffrey Woods (University of Cambridge, UK)
Stephen G. Waxman (Yale University School of Medicine, New Haven, CT, USA)
(C) Nature press release.
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