Alterations in the deoxyadenylate regions of the DNA from four human breast tumors

The levels of (dA) regions in 4 breast tumor DNAs were compared with the level in normal DNA. Although the (dA) regions in normal DNA remained constant in breast tissue, lymphocytes and placenta, (dA) alterations from the normal pattern were observed in the DNA from all four breast tumors. Tumor histology varied and was parallelled by a corresponding variation in the (dA) alterations following a quantitative analysis of the (dA) rich and (dA) “pure” sequences. The (dA) alterations associated with 2 of the tumor DNAs were distributed into both A + T rich and G + C rich DNA fractions.