Narrator: This is Science Today. Each year literally thousands of women are treated with fertility drugs and there's a tremendous variation between individuals. Jimmy Spearow, an assistant research geneticist at the University of California, Davis has found in mice studies, that many of these differences are genetic.
Spearow: In the case of humans, they really don't know what's causing the tremendous variability between individuals. Yet, our data and in mice and also other species, show that much of the differences are actually genetic - we found six to twenty-fold differences in the way that females respond to the same dose of a fertility drug, ie. a gonadotropin.
Narrator: Spearow and his colleagues have mapped several of the genes controlling these major differences in ovulation.
Spearow: Once we've identified those genes we can now use them as diagnostic markers. For example, if a woman has high hormone response genes you would know to give this individual a low dose of a fertility drug or to use a therapy which totally bypasses their genetic defect.
Narrator: For Science Today, I'm Larissa Branin.