41.   This meant that those genetic sequences had not existed long enough for them to undergo much genetic variation through mutation.

42.   Though all the populations of chinook are the same species, scientists have determined that significant genetic variation exists among the different runs.

43.   Those samples would yield cells whose nucleus contains DNA that has a unique pattern of genetic variations, Wahl said.

44.   Understanding these differences has spawned the field of pharmacogenetics, which explores how genetic variations influence the way people react to medicines.

45.   Will we see genetic variation as an economically efficient way to divide people based on group or individual risk of disease?

46.   A test is already available for this particular genetic variation, and many cancer doctors routinely offer it before starting children on chemotherapy.

47.   But as scientists sort out how these genetic variations influence response to drugs, they say pharmaceutical companies will use the information to build better medicines.

48.   Genetic variations that were held in reserve begin to trigger.

49.   He said several more genetic variations of the herpes virus need to be tested on mice to determine which is best for killing the cancer without infection.

50.   However, Dr. Christine B. Ambrosone of Mount Sinai School of Medicine in New York City said it someday may be useful to screen girls for the genetic variation.