People who feel no pain

http://www.bbc.com/future/story/20170426-the-people-who-never-feel-any-pain

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This is a brilliant report, containing links to several parts of the IB Biology syllabus. The few 100 people around the world who suffer from Congenital Insensitivity to Pain (CIP), feel no pain whatsoever. Their sensory pain neurons (nociceptors) are inhibited from generating an action potential by mutation of a gene named SCNP9A, which helps determine the structure of a specific voltage-gated protein channel for sodium (Nav1.7), on the membranes of nociceptors. You might think that inheriting this mutation is good. What better than to not feel pain? You would be very wrong. Many CIP sufferers die early as a result of the damage done to their bodies. This observation in itself is a neat piece of evolutionary natural selection – the CIP condition is so very rare because sufferers do not survive to pass the mutant version of the gene on to their offspring.

The mutation of gene SCNP9A is a missense or point mutation, where just one nucleotide is replaced incorrectly, so leading to mRNA carrying a codon for a different amino acid in translation and protein synthesis.

A spin-off from this research is now a race between different pharmaceutical companies to come up with a magic drug which might somehow work as an anaesthetic in patients suffering extreme pain, by inhibiting the Nav1.7 sodium channels in nociceptors. A new drug of this kind would be very specific to pain neurons and would be a replacement for the billions of painkilling tablets used every year throughout the world.

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