Pharmacogenomics, the search for individual factors that influence responses to drug treatment, depends on the identification of the genes responsible for individual differences. Last week's issues of the Journal of the American Medical Association and Human Molecular Genetics contained several reports that highlight progress in the understanding of the effects of individual genetic background on susceptibility to disease.

Identification of susceptibility genes may appear to cloud the picture of disease physiology, but in some cases adding more genes to the puzzle can focus attention on one point for therapeutic intervention.