- Mutation analysis of the CHK2 gene in breast carcinoma and other cancers. Ingvarsson, S., Sigbjornsdottir, B.I., Huiping, C., Hafsteinsdottir, S.H., Ragnarsson, G., Barkardottir, R.B., Arason, A., Egilsson, V., Bergthorsson, J.T. Breast Cancer Res. (2002)