The human genome has unifying messages as well as the potential to divide

With the publication of the sequence of the human genome, we can now approach our history as human beings in a way never previously possible—a history that has been written in only 30 000 or so genes. There is a completely different way of looking at history and genetics, however—one that should never be forgotten by clinicians.

Take a real case history: a 27 year old woman presents for a routine examination with a small lump on her breast. She had been seen by doctors who ignored the lump and took neither a biopsy nor an adequate history. The latest doctor to see her asked whether members of her family had had breast cancer. Both her mother and maternal grandmother died before the age of 40 from breast cancer. Whether their malignancies were caused by mutations in BRCA1 or 2, the p53, or other genes is unimportant: an adequate history would have revealed a great deal about her genetic susceptibility to disease. Classic papers, 1 2 largely but not entirely forgotten,3 point out that 70% of diagnoses can be revealed in clinical histories, with laboratory diagnosis accounting for only about 10% additional information. For clinicians in developing countries, without access to advanced diagnostic facilities but with knowledge of genetic research, a careful history can reveal much of what modern genetics and high technology can teach that is important …