However, the researchers quicly realised that those individuals with a mutation on only one of these copies (i.e., being heterozygous for that particular SERPINE1 mutation) didn’t have the bleeding disorder. Similar to heterozygous carriers of the sickle-cell anemia gene (HgbS gene) who have protection against malaria, people with this mutation appeared to experience advantages too. The answer was that they had a longer average lifespan and 10% longer telomeres, which is the small protective cap of repeated nucleotides at the ends of chromosomes. The caps in particular, tend to shorten and unravel over an organisms lifetime, and have been linked with the biology of aging.

Furthermore, those with a single copy of the mutation had a lower incidence of diabetes, lower insulin levels after fasting. slightly lower blood pressure, and possibly more flexible blood vessels. Of the 177 people in the community, 43 people had a single mutated SERPINE1 copy.

Thus, for the first time in this study a molecular marker of aging (telomere length), a metabolic marker of aging (fasting insulin levels) and a cardiovascular marker of aging (blood pressure and blood vessel stiffness) in combination point in the same direction in that these individuals were generally protected from age-related changes.