As we get older, the ends of our DNA, the telomeres, get shorter until replication goes haywire and we join the downhill race with our contemporaries, hoping to finish last. But it is not just the frazzled ends of our DNA that shows that we’re getting towards our use by date. Epigenetic modification does it too. Brockland et al of U Cal, LA have published a new study quantifying some of these effects (1).
In the early stages of our development, methyl groups get tacked on to some of the cytosine blocks of our DNA. This controls the activity and helps the cells remember what they are supposed to be. There are lots of unmodified cytosine molecules and those next to guanine form little islands – CpG islands. Brockland et al studied the methylation of two cytosine sites in three genes to see how this correlated with age.
The experimental program looked at 34 male identical twins so that random chance methylation could be ruled out. The twins were aged between 21 and 55. Then a larger group of men and women were asked to spit in a cup. Their ages ranged from 18 to 70. The results from all that saliva? Well, the predicted age of the participants was within spitting distance of their actual age. That is, their age could be predicted within about 5 years on average.
The paper suggests that this could be a useful tool for forensic guys, and that may be so. But a much more exciting possibility is the use of the method to look at the difference between chronological age and a patients biological age. We could all try hard to keep our DNA younger than our years and not just rely on our mirror. Also we could get tailored programs of health care to get us back on track and beat that ticking clock. Picture the day when we can drop into our local pharmacy, spit, and shortly after take our computer printout to the supplement counter.
