"No Pain, No Gain": Congenital Analgesia, Its Causes, and Its Relations to the Input/Output Theory
Congenital analgesia is a rare condition in which children, usually from birth, do not sense physical pain coming in from outside stimuli. Children with this rare condition often times break bones, lose teeth, get many cuts, bruises and bites without the body even knowing, and this can potentially dangerous, for the obvious reasons. Those who experience congenital analgesia can still feel touch, sensation, and normal body-to-body contact, which tells us that the brain can receive some information filtered through the nervous system; however, when it comes to extreme temperature changes, or any bodily damage that signals the body to react in an emergency fashion, the body instead does not respond. (1) This is a scary thought indeed, for only a very small percentage of our neural connections actually deals with communicating with the outside world, and because there are so few it seems as if we would need all of them! In the case of those with congenital analgesia, the input is either not being perceived or the input is being perceived, but the body knows no matching output.
Upon reviewing some notes taken some weeks back, I noticed where I was having trouble with the idea that the body receives inputs and the body produces outputs, but that they can either be in relation to one another, or be completely independent of each other. As a biology major, I was taught that for every action, there is a reaction; for every stimulus, there is a response; and for every thing that you put in, you can always get it back out. But I see now, that this is not always the case, as in the case of congenital analgesia. There are two sub-divisions of this condition: insensitivity to pain and indifference to pain.(1) Those who have an insensitivity to pain cannot interpret harmful input; those who have an indifference to pain can interpret the harmful input, but cannot match/pinpoint an output. These notions further explain how inputs and outputs can co-exist or work independently, especially in the case of pain indifference, where inputs are surely coming in, but outputs are not coming out.
Congenital analgesia, an autosomal-recessive trait, has been linked to a mutation in the SCN9A gene. (1, 2) Any slight mutation of this gene makes it completely non-functional, disabling the brain’s ability to interpret input pertinent to health. More scientifically, the SCN9A gene is important for encoding the alpha-subunit of the voltage-gated sodium channels, which are responsible for assisting in action potentials and signal firing amidst our neural connections in the body and brain. (2) Experiments done by Cox, et. al, shows that SCN9A, when mutated, produces sodium channels that do not function well, resulting in a decreased signal firing rate, whereas in wildtypes whose SCN9A gene was normal, the sodium channels assisted in action potentials and signal firing was normal.
Knowing about congenital analgesia, its causes, and its relationship to the input/output theory that we discussed in class can be quite beneficial to us in future research, for example we can create medicines to dramatically increase pain inhibition in such as cases as war or painful disease. However, the new question that I pose to my readers is now that we know about congenital anakgesia, it causes, and its relationship to the input/output theorem, how can we further use such a rare condition to our benefit, and what would Emily Dickinson have to say about this condition? According to her, it is all in the brain, it is a construct of our brain; but is it really?
(1) “Congenital insensitivity to pain” http://en.wikipedia.org/wiki/Congenital_analgesia
(2) Cox JJ, Reimann F, Nicholas AK, Thornton G, Roberts E, Springell K, Karbani G, Jafri H, Mannan J, Raashid Y, Al-Gazali L, Hamamy H, Valente EM, Gorman S, Williams R, McHale DP, Wood JN, Gribble FM, Woods CG. An SCN9A channelopathy causes congenital inability to experience pain.2006. Nature: 444, 894-898