A recent study conducted in Peruvian women, a population with relatively high average of Indigenous American (IA) ancestry proportion, reported a 20% increase in the odds of developing HER2-positive breast tumors per every 10% increment in the IA ancestry fraction (OR=1.20, 95% CI, 1.07-1.35, p=0.001) (20), and this association was especially strong for ER-negative tumors. The gene discussed is ERBB2; the disease is breast neoplasm.