PARIS, Dec 13: A Pakistani child who earned a living by stabbing himself with knives as a street performer before he met a tragic death may have helped open the way to a new generation of smarter anaesthetics.

The boy helped scientists explain a phenomenon that is not only extraordinarily rare but -- depending on the viewpoint -- is also either a curse or a blessing: why some people in the world are naturally immune to pain.

In a paper published on Thursday in the British journal Nature, a team of geneticists and neuroscientists describe how the boy from northern Pakistan, then aged 10, came to their attention.

The child was well known to local doctors because he took part in “street theatre”, pushing knives through his arms and walking on burning coals, sometimes suffering injuries but never feeling any pain. The child, who is being kept anonymous, died on his 14th birthday after jumping off a house roof.From this single case, the scientists fanned out, identifying three families in northern Pakistan who were related to the boy. Six people within this group also had immunity to pain -- a “cluster” in scientific parlance that is a golden lead for investigators to follow.

The six included three children aged six, four and 14 in one family; a child aged six in another; and two children aged 12 and 10 in the third family.

“All six individuals had never felt any pain, at any time, in any part of their body,” the authors say.

“None knew what pain felt like, although the older individuals realised what actions should elicit pain, including acting as if in pain after football tackles.” All had injuries to their lips and tongues from accidental bites -- in fact, two of the six had lost the last one-third of their tongues through this -- and had suffered frequent bruises and cuts.

They also suffered from badly-mended fractures. A broken leg or arm would be spotted only in retrospect, thanks to painless limping or the lack of use of the limb.—AFP