The year is 2003. A nurse draws blood from a pregnant woman for a routine prenatal exam. In the blood are a few immature red blood cells from the fetus. The nurse sends the blood sample to a laboratory, where a technologist, using an instrument that recognizes and separates out unusual cells, collects a few fetal cells.
An initial peek within the cells, at the chromosomes that carry genes, reveals the first piece of information-the individual will be a boy, shown when a fluorescent dye highlights a Y chromosome in each cell. A closer look at specific genes reveals much more.
Happily, the future child will not have any of the more common inherited disorders. Despite the apparently healthy genetic background, some blood cells from the umbilical cord will be set aside at birth and deep-frozen. Should he one day require a bone marrow transplant to treat life-threatening anemia or cancer, his own cord blood cells will be infused into his body where they will grow ne bone marrow, tailor-made for his body.
Other results from the prenatal test indicate that the boy will be able to minimize effects of certain potentially unhealthy inherited characteristics. Tests to type the genes that predispose him to develop heart disease make it clear that a lifelong low-fat diet and regular exercise can extend his life. The same measures can help prevent or delay colon cancer, since he has inherited a pair of susceptibility genes. A computer evaluates how certain genes affect expression of other genes. Many inherited traits are not checked because they will not affect health. Hair and eye colour and freckles will remain surprises.
This scenario takes place in the near future, but every one of the tests described is performed today. Other genetic screening tests, for fetuses as well as newborns, have been available for many years. Many new tests to detect genetic disease susceptibilities are being developed. They are raising questions for the health insurance industry on how to handle future illnesses.
Until recently, we didn’t know the nature of most genes that cause disease. However, a global scientific effort called the human genome project is rapidly adding more genes to the collection of those we can test for as it deciphers the complete genetic makeup, or genome, of humans.
Once a basic life science, human genetics is rapidly becoming a medical discipline. The human genome project is altering the way view illness and is also revealing the many ways that people differ from each other.