HEALTH & SCIENCE
If you've ever wondered why the rest of your
family towers over you in height - it may be down to a rare genetic misfortune
which has left you with a miserable batch of 'short genes'.
Scientists at the the University of Exeter
conducted a study to find out what factors determine a person's height.
They discovered that one fifth of the genetic
factors that cause height to vary between siblings is that the smaller brothers
and sisters have 'simply inherited a big batch of short genes.'
The study also found while it was commonly
thought we are taller than our ancestors thanks to better diets, this factor is
only responsible for a fifth of the growth spurt.
Four fifths is down to genetics passed on from
one generation to the next.
The study is the largest of its kind in history
and also revealed that more than half of the factors involved in
determining height are explained by the simple common genetic variation - the
differences between and among different populations.
By examining the DNA from more than 250,000
Europeans, researchers from the international GIANT consortium checked more
than two million common genetic factors - those shared by at least five per
cent of participants.
From this they found 697 genetic variants in 424
regions of the genome, the genetic material of an organism, that are related to
height.
Before 2007 virtually nothing was known in this
area of research.
Professor Tim Frayling of Exeter's Medical
School said: 'It's common knowledge that people born to tall parents are more
likely to be tall themselves.
'Most of this is down to the variations in our
DNA sequence that we inherit from our parents - the different versions of all
our genes.
'In 2007 we published the first paper that identified
the first common height gene, and since then the research has come on leaps and
bounds.
'We have now identified nearly 700 genetic
variants that are involved in determining height.
'This goes a long way towards fulfilling a
scientific curiosity that could have real impact in the treatment of diseases
that can be influenced by height, such as osteoporosis, cancer or heart
disease.
'It also a step forward towards a test that may
reassure parents worried that their child is not growing as well as they'd
hoped - most of these children have probably simply inherited a big batch of
'short genes'.'
Dr Andrew Wood added: 'Our findings have helped
to identify a large proportion of the genetic architecture that contributes to
determining our height.
'We know that as a population we have become
taller over the last few generations, because of factors including improved
nutrition. But more than 80 per cent of the factors in height variation are
known to be down to genetics, with the rest caused by environmental factors.
'Thanks to advances in technology, we now have
access to far greater quantities of DNA data.
'These data sets are proving to be a genetic
treasure trove which has enabled us to shed light on height, and we expect to
continue to make significant advances, both in this field and in other human
traits.'
'Our results suggest that massive human genetic
studies, possibly into the millions, will continue to uncover all the subtle
effects of our genetic variation that influence our health, behaviour, body
shape and all aspects of what makes us who we are.'
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