The finding paves the way for a DNA test to screen for those people who are at the most risk of becoming drug addicts or alcoholics.

In a study of 3,627 volunteers, the researchers found that women of European origin with a mutated version of a gene, known as PKNOX2, were almost twice as likely to become substance abusers than those without the variant. 

The gene was linked with alcohol addiction in mice in research published several years ago, but until now was never reported as being associated with substance abuse in humans.

Source: http://blog.taragana.com/health/2009/09/01/addiction-gene-puts-white-women-at-high-risk-of-becoming-drug-booze-addicts-11099/