A GENE test that predicts when one will die? This seemingly speculative theory bas now become a distinct reality, thanks to fresh research carried out at the Rockfeller University, us. Researchers at Rockfeller have identified the apolipoprotein-F, or apo-F gene as the first of a set that roughly determines normal longevity. "Apo-F is one of those genes that we suspect controls lifespan, because it affects people's susceptibility to diseases of aging," says fan Vigh, a molecular geneticist at Beth Israel Hospital in Boston. The Apo-E gene and its protein have three different versions. There are six possible combinations of the protein because everyone has two copies of each gene. But 75-80 per cent of us are born with at least one E-3 ver- sion of the protein and more than half have two E-3s. Scientists are particularly excited about people with one or - more rarely - two copies of the F,-4 and E-2 versions of the gene. According to researchers, people with a copy of E-4 seem least likely to enjoy longevity while those with an E-2 are the most likely to five for a century.