Humans: Not as Genetically Identical as We Thought
Differences that one reading of our genetic code put at 0.1 per cent. are, according to the new way of reading, put at 12 per cent. — 120 times greater. Quasi-religious equalitarian claims of universal human equality are becoming more and more difficult to sustain.
WHAT’S PREVIOUSLY BEEN taught is that of the 6 billion or so people on the planet, we all share 99.9% of each other’s genes and identity. These results came from the Human Genome Project five years ago and are now assumed to be very much wrong. Last month, research was published in the journal Nature and ABC Science News reports that we are genetically more varied than what was once assumed.
The analysis of the genome has been focused mainly on comparing differences, or ‘polymorphisms,’ in the patterns of single letters in the chemical code for making and sustaining human life. But now, a group of scientists from around the globe have come from a different angle and believe they have uncovered a complex, higher-order variation in the code.
This large difference in code between individuals can now explain why some people are vulnerable to certain diseases and respond well to certain drugs, while others fall sick quickly or never respond to treatment.
What the scientists have been doing is digging out deletions or duplications of code among relatively long sequences of individual DNA and then comparing these ‘copy number variations’ across a range of volunteers of diverse ancestry.
The researchers were stunned that they were able to locate 1447 copy number variations in nearly 2900 genes, which is about one eighth of the human genetic code.
Dr Matthew Hurles from the Wellcome Trust Sanger Institute in the UK is one of the project’s partners and says that “Each one of us has a unique pattern of gains and losses of complete sections of DNA. One of the real surprises of these results was just how much of our DNA varies in copy number. We estimate this to be at least 12% of the genome.”
The group found that almost 16% of genes that are known to be related to disease have these copy number variations. The diseases involved include rare genetic disorders like DiGeorge (caused by the deletion of a piece of chromosome number 22), Williams-Beuren (otherwise known as ‘Pixieism’) and Prader-Willi syndromes and those linked with schizophrenia, cataracts, spinal muscular atrophy and atherosclerosis.
But kidney disease, Parkinson’s, Alzheimer’s and vulnerability to malaria and HIV, which recent research has blamed on single-letter variations in the gene code, may also well be rooted in CNVs, the scientists believe.
Consequences of this recent research could benefit medical diagnosis and new drugs.