Congenital insensitivity to pain
How rare is congenital insensitivity to pain?
Since 1932, about 50 cases of congenital indifference to pain have been reported. Fewer than 1 in 1,000,000 are affected.
Golshani, Ashkahn E., et al. "Congenital Indifference to Pain: An Illustrated Case Report and Literature Review." Journal of radiology case reports 8.8 (2014): 16.