Given the paucity of data on genetic variability of CHEK2 in Asian populations coupled with the fact that less than 20% of Pakistani women with early-onset or familial breast/ovarian cancer can be attributed to germ line mutations in BRCA1, BRCA2 and TP53[38,39], we assessed the prevalence of CHEK2 mutations in 145 high-risk BRCA1/2-negative breast/ovarian cancer patients from Pakistan (Group 1). This evidence concerns the gene BRCA1 and ovarian cancer.