Abstract
Microchimerism (MC), transplacental acquisition of allogeneic cells from the mother (maternofetal MC) or from the fetus (fetomaternal MC) has been in the focus of research recently. Amplicons using Y-chromosome specific SRY and DYS14 sequences have been used as markers to trace cells from a male fetus in the mother. The sensitivity of these markers in formaldehyde fixed paraffin embedded samples, however, is less than optimal. To study chimerism in breast cancer we took advantage of the evolutionary history of the Y chromosome and designed amplicons on gene repeats to generate additive PCR signals. The increased sensitivity detected high incidence of male chimerism in normal breast tissues. We also showed correlation with protection from cancer with unique quantitative biology. Accumulating data from biology and medicine indicate that natural chimerism is astonishingly frequent and may affect human conditions. We hypothesize that it has significant evolutionary ramifications as well.