View Full Version : *MAJOR* DNA advance....

Dr Mordrid
22nd November 2006, 20:25
This is just a taste. Full read recommended.


Genetic breakthrough that reveals the differences between humans

Scientists hail genetic discovery that will change human understanding

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.

Fat Tone
23rd November 2006, 01:00
Thanks Doc. All we got about that on Radio 4 this morning was "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". We did get several minutes of speculation on the 'poisoned' Russian chap though. :rolleyes:

28th November 2006, 04:50
The full text is even more interesting.

Deletions are known to be biased away from genes5, as a result of selection. In contrast, the selective pressures on duplications are poorly understood; the existence of gene families pays testament to positive selection acting on some gene duplications over longer-term evolution42. We identified the different classes of functional sequence that fell within CNVRs, and tested whether they were significantly enriched or impoverished within these CNVRs compared to the entire genome (Table 1; see also Supplementary Table 13 and Supplementary Methods).

We found CNVs in genes already known to be responsible for complex traits, including CCL3L1 and FCGR3B19, 20. Some new observations were also documented. Two CEU samples (mother and offspring) manifested a gain of CNV-95 involving the first six exons of DISC1, which is disrupted in schizophrenia48. CNV-575, encompassing the LPA apolipoprotein A gene, demonstrated population variability, which may influence susceptibility to atherosclerosis. The CRYBB2-CRYBB3 -crystallin genes in CNV-1367 were observed as gains and losses in copy number in CEU and YRI samples. However, only gains were detected in Asians, leading us to speculate that variability in crystallin copy number may be linked to population differences of onset of age-related cataracts49. Following a similar rationale, we highlight CNV-507 for possible involvement in sarcoidosis owing to its proximity to the BTNL2 gene50, and CNV-505 in psoriasis susceptibility, because it covers the 6p21.3 (PSORS1) susceptibility locus51.


This is also interesting:

The HapMap collection comprises four populations: 30 parent–offspring trios of the Yoruba from Nigeria (YRI), 30 parent–offspring trios of European descent from Utah, USA (CEU), 45 unrelated Japanese from Tokyo, Japan (JPT) and 45 unrelated Han Chinese from Beijing, China (CHB). Genomic DNA from Epstein–Barr-virus-transformed lymphoblastoid cell-lines was used.

30 parent–offspring trios of European descent from Utah, USA but no americans where actually included in the study...
I can understand the complications but it would be interesting.
For example: considering that all (caucasian) americans are of european origin the data would give us an idea of how fast are these changes taking place:

are all regions affected or just a few? or none of them?
how much can a few hundred years affect those regions?
not to mention that if there were any genes or gene promoters affected we would have an idea of the flexibility of the human genome....

Dr Mordrid
28th November 2006, 05:02
Yup. Overall it highlights just how little we do know about DNA. It should definitely spawn a ton of new studies.