BRCA1 and cancer: Among the 100 genes examined in this study, only two of the top 10 highest Alu density landscapes are associated with deletion-prone cancer genes, ARID1A and BRCA1. These two genes rank 8th and 10th in this list with Alu landscape densities of 1,322 and 1,309 Alus per mega base, respectively (see Table S3).