CDKN1A and breast cancer: The genome-wide copy number alteration analysis of breast cancer in South African women (153) identified the amplification in Xp22.3 and 6p21-p25, and other regions that affect known cancer genes like CCND1, CDKN1A, MDM2, TP53, and SMAD2. Meanwhile, the whole-exome sequencing study by Hamdi et al. (152) and Riahi et al. (156) linked breast cancer in Tunisian women to alterations in MMS19, DNAH3, POLK, KATβ6, and RCC1 in BRCA1/2 mutation-negative patients with familial breast cancer.