Beyond genomics.

The sequencing of the human genome has already had an enormous impact on medicine, particularly with single-gene changes that predispose to a serious disease such as cystic fibrosis or the overexpression of Her2 in about one-third of breast cancers. Genetic technology has led to some very important therapeutic innovations, including the use of imatinib mesylate (Gleevec) in BCR-ABL chronic myeloid leukemia and of trastuzumab (Herceptin) in Her2-positive breast cancer, but the much anticipated explosion of new effective treatments has been more modest than expected.