altyfc
Joined: 27 Jul 2004
Location: Aardvarkland
Posted: Thu Oct 27, 2005 2:33 pm
|
  Post subject: Post-It note may hold cancer clue
It is a feat akin to sticking a million Post-It notes into the tedious book of 3 billion letters that is the human genetic code, so that the important bits are easy to find.
By studying the DNA of more than 250 people from Nigeria, Japan, China and the United States, researchers have identified 1 million of the most common genetic differences among people worldwide that could hold the clues to diseases like asthma, diabetes, cancer and heart disease.
The sequencing of the human genetic code five years ago revealed our extraordinary similarities: any two unrelated people are 99.9 per cent identical at the genetic level.
But it is the 0.1 per cent variation that will be important for determining why some individuals are more susceptible to a particular disease or respond differently to a drug, toxin or other environmental factor.
Developing the new catalogue of these common variations - known as a HapMap - took a private and publicly funded international consortium of more than 200 scientists three years of work.
Yusuke Nakamura, a team member and director of the University of Tokyo’s Human Genome Centre, said it would reduce the cost of looking for the genes linked to common diseases by up to twentyfold.
“The HapMap is a phenomenal tool that is making possible research that was impractical, if not unimaginable, only a few years ago.”
Tom Hudson, another team member, from McGill University in Montreal, likened the research to the first flight across the Atlantic Ocean. “Once the trip was done, travel was changed forever. Human genetics has just crossed a similar barrier.”
One of the first uses of the research, which is published today in the journal Nature, has been to identify a genetic variation that substantially increases the risk of the age-related eye disease macular degeneration, the leading cause of severe vision loss in the elderly.
The tiny variations the scientists looked for by studying 269 people were sites in the genetic code where the DNA sequence of many individuals varied by a single letter. There are an estimated 10 million of these sites, known as single nucleotide polymorphisms, or SNPs (pronounced snips) in the human population.
However, they tend to be inherited in groups, called haplotypes, hence the term HapMap.
Researchers studying complex diseases, like diabetes, which are affected by many genes as well as environmental factors, will compare the haplotypes of individuals with the disease to those without.
It is hoped that finding haplotypes linked to the disease will narrow down the search for the genetic variations, or SNPs, responsible.
A second version of the HapMap being developed by the team will contain more than 3 million SNPs.
Aaron
|
