Sunday, October 28, 2018

How Old Are You?

Simple, straightforward question; but often the answer isn't either.   If only we could develop an Agemeter (or should it be Ageometer? )  just like the thermometer  for body temperature!. An  ageometer   with a  precision of 0.5  to give readings like 17.5,  18.0, 18.5, 19 .....    Age has always been important from the  medico-legal angle,  because  it bestows  varying levels of  rights and responsibilities on children, juveniles and adults and at times senior citizens. Currently a combination of methods are used to assess the age of an individual - examination of teeth, wrist bones etc.  But the error margins are often 3-4 years. 

Age Factor  has now spilled  beyond  medico-legal boundaries into  geo-political and socio-economic arena.  The recent mass  influx of refugees into  Europe is the single biggest  thrust  factor.   According to  recent reports  Europe has close to 4 million refugees.  As per the UN requirements,  asylum seekers   under the age of  18 are eligible for special benefits and that means  a drain on national resources.   A population fleeing from its war torn homeland can't  think of,  let alone pause to pick up  passports or birth certificates. Moreover families get separated often with none to vouch for the age of  orphaned youngsters. There is widespread   feeling that  refugees  deliberately forge their age to qualify for special benefit package.  With nationalism on the surge all over the world, resentment  against refugees are flaring up everywhere. 
    

It is in this context that  the Epigenetic Clock proposed  by Professor Horvath  (Dept. of  Genetics and Biostatistics, University of California, Los Angeles, USA) catches global attention.   There is scientific concurrence that   DNA methylation levels (referred to as DNAm), could be a measure of  the mammalian ageing process, though   the "How" and "Why" of the correlation remain blurred. Methylation  happens at the  cytosine nucleotide linearly attached to a guanine nucleotide. These are referred to as CpG sites.    Methylated CpG sites are thus  biomarkers, which have the potential to turn off genes. In his approach Prof Harvoth used  a special machine learning method  to identify  the biomarkers  located at informative genomic locations and then  an algorithm to predict the biological age.  Initially selecting  353 such sites,   Prof Horvath  demonstrated that this  method  could spell out the biological age for a majority of tissue  samples with a median error of 1.03 years.  However it is also a fact that  there were outliers with error margin as high as 5 years.  While scientists are focusing on improving the accuracy of the method,    Zymo a company based in Irvine, California bought exclusive rights for the technology.  DNAge Epigenetic Aging Clock service is now available for US$299.     

Tailpiece
The Old Town Hall  is one of the oldest buildings in Prague, dating back to 1338.  The astronomical clock installed in 1410  is the oldest, still ticking  astronomical clock in the world. 


Town Hall Tower with the
Astronomical Clock  




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