One study conducted in Hunan, China, first reported two variants in the PTEN gene (225A> C (T160P) and IVS5 +13T> C) and two variants in the NBS1 gene (IVS6 + 43A> G and IVS6 + 127A> G) in familial and early-onset BC in the study population (130). Here, NBN is linked to breast cancer.