The identification, however, is unlikely to lead to a treatment for cocaine addicts.
But the research team hopes that the discovery could be used to screen for those most likely to have problems kicking the habit if they ever try the drug.
"If you are a carrier of this gene variant, the likelihood of getting addicted to cocaine is higher," Guardian.co.uk quoted Rainer Spanagel, a professor of psychopharmacology at the Central Institute of Mental Health in Mannheim, Germany, who led the study, as saying.
"You can certainly use this as a vulnerability marker for cocaine addiction," the expert added.
The researcher said people found to be susceptible to cocaine addiction could be given counselling or protected with experimental vaccines now being developed.
The vaccines are designed to block the "high", or euphoria, associated with the drug.
Earlier, an analysis by the European Union's drug agency had put Britain at the top of its list of cocaine-abusing states.
Scientists believe that genetic factors account for 70percent of cocaine addiction. Studies of twins suggest alcoholism is about 50percent genetic.