PCDH18 and breast cancer: The recent whole genome sequencing (WGS) of 560 breast cancers samples identified 89 genes and 2433 breast cancer sequencing projects identified 40 breast cancer drivers genes from ER positive and ER negative breast cancer subtypes and many of these genes such as ARID1A, CTNND1, NUP107, CHD8, FANCI, CHD9, CTCF, KEAP1, PCDH18, LAMA2, HDAC9, ARFGEF1, MLLT4, FOXO3, CDKN2A, MAP3K1, GPS2, CTCF, CDH1, GATA3, AKT1, etc. have diversified functional change mutations [17, 52].