Breast cancer affects women at relatively high frequency (1). We mined published microarray datasets (2, 3) to determine in an unbiased fashion and at the level of the transcriptome genes most differentially expressed in the primary tumors of patients with early-onset breast cancer. We found significant differential expression of the gene encoding DNA methyltransferase 3A, DNMT3A, when comparing primary tumors of the breast to the tissue of origin, the normal breast: in women aged 45 and

more »

... , and women aged 70 and higher. DNMT3A mRNA was present at significantly higher quantities in tumors of the breast as compared to normal breast tissue. Analysis of human survival data revealed that expression of DNMT3A in primary tumors of the breast was correlated with overall survival in patients with luminal B subtype breast cancer, demonstrating a relationship between primary tumor expression of a differentially expressed gene and patient survival outcomes influenced by PAM50 molecular subtype. DNMT3A may be of relevance to initiation, maintenance or progression of cancers of the female breast.