In an additional examination of 138 alcoholic Finnish men, many of whom displayed high levels of novelty seeking, the D4DR variation appeared slightly more often among those with the lowest scores on that personality trait, the researchers hold.
Kidd's team, which presented its findings this week at the American Society of Human Genetics annual meeting in San Francisco, assessed D4DR variations in 14 populations from Africa, Europe, the Middle East, East Asia, North America, and South America.
Studies that discerned a link between this D4DR form and novelty seeking took place in Israel and the United States, where the gene is relatively frequent, they state.
Preliminary data gathered by Kidd's team indicate that chimpanzees, gorillas, and orangutans exhibit other DNA variations in a region that corresponds to the part of the human D4DR gene where repeated sequences are found.
However, prior studies have found that the same patients do not exhibit a preponderance of any particular form of the D4DR gene.
It may be useful to reexamine D4DR in groups of schizophrenics to find how often the longer variety occurs together with novelty seeking, Cloninger contends.