The RAD51 protein and its paralogs (RAD51B, RAD51C, RAD51D, XRCC2 and XRCC3) are recruited to form a helical nucleofilament on the exposed single–stranded DNA (ssDNA) for the maintenance of genome stability in mammalian cells.36 In humans, the functions of the paralogs as mediators of HR demonstrate important tumor suppressor activity. The gene discussed is XRCC2; the disease is neoplasm.