In addition, there were also studies investigating the association between BC risk and DNA methylation (Kuchiba et al., 2014), length of CAG repeats (of androgen receptor alleles) (Chen et al., 2014a), mitochondrial DNA content (Jiang et al., 2014), mitochondrial D-loop insertions (Tipirisetti et al., 2014), and telomere length (Qu et al., 2013). Here, AR is linked to breast cancer.