When was congenital-analgesia (aka congenital insensitivity to pain), the inability to feel pain, clinically documented?
It was first reported in 1932 in this paper:
Dearborn, G. V. N. (1932). A case of congenital general pure analgesia. Journal of Nervous and Mental Disease, 75, 612-615. http://dx.doi.org/10.1097/00005053-193206000-00002
However, I tried reading it, the print is very faded and near-impossible to read.
How rare is it really?
1 in 125 million
Daneshjou, K. et al. (2012). Congenital insensitivity to pain and anhydrosis (CIPA) syndrome; a report of 4 cases. Iranian Journal of Pediatrics, 22, 412–416.
But in this paper on the epidemiology in Japan, it's estimated at 1 in 600,000–950,000
Haga, N., Kubota, M., & Miwa, Z. (2013). Epidemiology of hereditary sensory and autonomic neuropathy type IV and V in Japan. American Journal of Medical Genetics Part A, 161, 871-874.
Is it hereditary? Or just a sporadic fluke mutation?
Congenital insensitivity to pain with anhidrosis (CIPA), also known as hereditary sensory and autonomic neuropathy type IV (HSAN IV)
Kim, W., Guinot, A., Marleix, S., Chapuis, M., Fraisse, B., & Violas, P. (2013). Hereditary sensory and autonomic neuropathy type IV and orthopaedic complications. Orthopaedics & Traumatology: Surgery & Research, 99, 881-885.
So what is the life expectancy of someone with congenital-analgesia?
There's age distribution of the population in Japan:
It doesn't say life expectancy, but it seems that it won't be past 40 years.