PCDH11X and breast cancer: Our group more recently discovered another in-frame ESR1 fusion gene involving the protocadherin 11 X-linked gene, PCDH11X (ESR1-e6>PCDH11X) provided by inter-chromosomal translocation that also produced stable ESR1 fusion protein identified in a patient with endocrine-refractory, metastatic ER+ breast cancer[75].