Likewise, population-specific differences in the frequencies of variants associated with drug metabolism may mean that certain drugs will be safer and more effective in some populations than in others. The CYP2D6 gene, for instance, is involved in the metabolism of many commonly prescribed drugs, including tamoxifen, which is used to treat breast cancer. More than 100 different variants of this gene (alleles) — many of which affect an individual’s ability to safely digest and use a drug5 — occur at different frequencies in different populations.
