Genetic components of human pain sensitivity: a protocol for a genome-wide association study of experimental pain in healthy volunteers by Schmid, AB, Adhikari, K, Ramirez-Aristeguieta, LM, Chacón-Duque, J-C, Poletti, G, Gallo, C, Rothhammer, F, Bedoya, G, Ruiz-Linares, A, Bennett, DL