Genetic breakthrough that reveals the differences between humans
By Steve Connor, Science Editor
Published: 23 November 2006

 

Scientists have discovered a dramatic variation in the genetic make-up
of humans that could lead to a fundamental reappraisal of what causes
incurable diseases and could provide a greater understanding of
mankind.

The discovery has astonished scientists studying the human genome - the
genetic recipe of man. Until now it was believed the variation between
people was due largely to differences in the sequences of the individual ”
letters” of the genome.

It now appears much of the variation is explained instead by people having
multiple copies of some key genes that make up the human genome.

Until now it was assumed that the human genome, or “book of life”,
is largely the same for everyone, save for a few spelling differences in
some of the words. Instead, the findings suggest that the book contains
entire sentences, paragraphs or even whole pages that are repeated any
number of times.

The findings mean that instead of humanity being 99.9 per cent identical, as
previously believed, we are at least 10 times more different between one
another than once thought - which could explain why some people are prone to
serious diseases.

The studies published today have found that instead of having just two
copies of each gene - one from each parent - people can carry many copies,
but just how many can vary between one person and the next.

The studies suggest variations in the number of copies of genes is normal
and healthy. But the scientists also believe many diseases may be triggered
by an abnormal loss or gain in the copies of some key genes.

Another implication of the finding is that we are more different to our
closest living relative, the chimpanzee, than previously assumed from
earlier studies. Instead of being 99 per cent similar, we are more likely to
be about 96 per cent similar.

The findings, published simultaneously in three leading science journals by
scientists from 13 different research centres in Britain and America, were
described as ground-breaking by leading scientists.

“I believe this research will change for ever the field of human
genetics,” said Professor James Lupski, a world authority on medical
genetics at the Baylor College of Medicine in Houston, Texas.