Quillen, E. E., Bauchet, M., Bigham, A. W., Delgado-Burbano, M. E., Faust, F. X., Klimentidis, Y. C., et al. (2012). OPRM1 and EGFR contribute to skin pigmentation differences between Indigenous Americans and Europeans. Human Genetics, 131(7), 1073-1080. doi:10.1007/s00439-011-1135-1.