- Genetic association of the R620W polymorphism of protein tyrosine phosphatase PTPN22 with human SLE. Kyogoku, C., Langefeld, C.D., Ortmann, W.A., Lee, A., Selby, S., Carlton, V.E., Chang, M., Ramos, P., Baechler, E.C., Batliwalla, F.M., Novitzke, J., Williams, A.H., Gillett, C., Rodine, P., Graham, R.R., Ardlie, K.G., Gaffney, P.M., Moser, K.L., Petri, M., Begovich, A.B., Gregersen, P.K., Behrens, T.W. Am. J. Hum. Genet. (2004)