Wednesday, 26 September 2012

Even the hairs on your head are all counted

The human genome is pretty amazing: it’s made up of 24 chromosomes, which between them contain about 30,000 genes, made up of over 3000 million bits (called “bases”). That's a lot of bases: if I were to count one of these bases every second, it would take me 100 years to count them all. And that’s inside essentially every one of the 50 trillion cells in your body.
It has been reported this week, in what is likely to be a very major outcome from the Human Genome Project, that it now seems that around 80% or so of the human genome is functional in one way or another. Whilst many people would assume that all of the human genome would be doing something, until very recently scientists thought this was not the case. Indeed, it has been known for some time that only about 2-3% of the human genome actually contained information that led to the production of protein molecules and thus to all the components of the body, whilst a further small percentage was involved in keeping the chromosomes structurally intact and still a further small percentage in the regulation of the activities of genes. The remainder of the genome was routinely referred to as ‘junk DNA’.

This latest discovery not only signals that the term ‘junk DNA’ must itself be junked, but also vastly revises the proportion of the genome involved in regulatory activities - scientists have identified about four million genetic 'switches' that modulate the activities of genes, and many of them are associated with changes of risk in disease, diseases as diverse as heart disease, diabetes and mental illness. This opens up whole new avenues of research into these diseases and thus may be very important in developing new therapies and preventative strategies, which is clearly to be welcomed. However, previously expressed concerns about genetic selection and/or modification do, of course, remain valid.

We still have a lot to learn about what it means to be human, but the Psalmist was certainly right when he wrote: “I praise you because I am fearfully and wonderfully made; your works are wonderful, I know that full well. (Psalm 139:14)

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