In support of this, the results presented in the present study demonstrated that 56% of breast cancer cell lines had undergone single copy number loss of four candidate hTERT-repressor genes (SETD2, BAP1, PBRM1 and PARP-3) spanning a 5.5 Mb region within 3p21.1-p21.3, which adds to the body of evidence that these genes play an important tumour suppressive role in breast cancer cells [20, 21, 26–30]. Here, PARP3 is linked to breast cancer.