Zhu et al. showed that a PER3 variant containing five variable number tandem repeats (VNTR; rs57875989) was associated with higher risk of developing BC compared to a PER3 variant with four VNTRs in young Caucasian women [44] (Table 1), but this association was not observed in other studies, which included Chinese [45], Indian [56] and multiple European cohorts [57]. This evidence concerns the gene PER3 and breast cancer.