Shared Alcohol Gene Reveals Asia/Pacific Ancestry
A genetic discovery by Dr Geoff Chambers of Victoria University has revealed that many Polynesians have inherited a genetic factor from Asian ancestors which may assist in reducing an overall risk of them developing alcoholism. The discovery also reveals information about Pacific migration patterns.
Dr Chambers’ research, started more than ten years ago, has been supported by the Alcohol Advisory Council and the Wellington Medical Research Foundation. Blood donors gave samples with informed consent and later blood was also provided by European and Polynesian men participating in alcohol treatment programmes. Dr Chambers says that the data from the blood donor samples show that more than two thirds of Polynesians have inherited a gene from Asian ancestors responsible for making the consumption of alcohol a less pleasant experience. In Europeans, fewer than one in ten carry the same gene.
This discovery of the gene ADH2*2 in Polynesian people adds to the understanding of where New Zealand’s indigenous people came from and the path they took to get here. Those Asians who are very sensitive to alcohol possess two genes which make alcohol consumption unpleasant: ADH2*2 increases the production of the toxic chemical, acetaldehyde, which is compounded by the gene ALDH2*2 which prevents the liver from detoxifying acetaldehyde. Of these two gene variants Dr Chambers has discovered that more than two thirds of Polynesians have inherited ADH2*2 from Asian ancestors, but not ALDH2*2. Research shows that the gene ALDH2*2 was carried from mainland China to Taiwan about 5000 years ago but migrated no further.
At very high levels acetaldehyde acts as a poison in the body and causes headaches, flushing and nausea. Those with ADH2*2 in their genetic kit are unlikely to drink alcohol to excess and are therefore unlikely to develop alcoholism. In contrast to the Asian and Polynesian group, almost all Europeans belong to a group that lacks ADH2*2: their bodies produce a lower amount of acetaldehyde, which the liver is able to effectively detoxify. So for most Europeans, drinking can be a more pleasurable experience, which leaves them open to developing alcoholism.
A third of the New Zealand Maori population, like Europeans, lacks ADH2*2. An analysis of blood samples of young Maori males with drinking problems showed that three quarters of them were drawn from this group.
Not only does Dr Chambers’ research provide genetic and historical insights into the origins of Polynesian people, but it also offers the most compelling evidence yet in support of genes being used to predict behaviour and influence lifestyle choices.
“One day these new molecular tools might give you a genetic profile, which you’d want to consider on a whole range of lifetime decisions beyond simply finding out whether you were genetically coded to process alcohol effectively,” he says.
“International statistics show that 5-10% of all adult males may become alcoholics and that up to a third of males may develop some form of alcohol dependency at some stage in their lives. If they knew that their genetic make-up predisposed them to alcoholism, then they would be in a better position to make considered decisions to modify their relationship with alcohol,” says Dr Chambers.
Further research might involve the social sciences, including sociology and psychology, to compare behaviour with genetics. “I’m interested in working with Polynesians to look at the drinking patterns of people with ADH2*2 genes to see if they drink lesser amounts of alcohol, and drink less often,” Dr Chambers says. “Previous studies of Asian peoples suggest very strongly that this should be the case”.
The study came about as an offshoot of Dr Chambers’ long-time research using genetic profiles to track the migration patterns of the indigenous peoples who populated New Zealand. The discovery of the shared ADH2*2 gene is further evidence to support his theories about their migrations.
Dr Chambers will outline his findings next month in leading American research journal ACER (Alcoholism: Clinical and Experimental Research) and in the New Zealand Science Review.
For further details please contact Dr Geoff Chambers, Institute of Molecular Systematics, Victoria University 04 463 6091 (wk) or 04 562 8450 (hm) or Juliet Montague, Public Affairs, Victoria University 04 463 5105.