The 1000 Genomes Project

jd writes "An international consortium of specialists in genetics has announced the 1000 Genomes Project, in which at least 1,000 people from around the world will have their genomes fully sequenced as part of an effort to discover the relationship between genetics and disease. At present, over 100 regions of DNA are known to be related to illnesses, but the maps that exist are vague and are drawn from an extremely small population pool. According to the article, this results in the need for slow, expensive, and laborious studies to pinpoint causes, especially for rarer conditions. This project aims to find conditions that might only appear once in every 2,000 people (though how they intend to do that with half that number is unclear). The researchers hope to massively speed up the diagnosis of genetically linked illnesses and to improve the reliability of such diagnoses."

Comments

1 in 2000 people

[rsidd]

This project aims to find conditions that might only appear once in every 2,000 people (though how they intend to do that with half that number is unclear)

Let's try to make it clearer, then.

The probability that a given condition appears in an individual is 1 in 2000, or 0.0005. The probability that it does not appear in that individual is 0.9995. The probability that it does not appear in any of 1000 individuals is 0.9995^1000 = 0.6 approximately; and the probability that at least one of the 1000 individuals has it is 0.4. Not bad at all. (If you used 2000 people, the probability that at least one of them would have it would improve to about 0.6.)

Suppose you aren't interested in just one conditions, but in lots of conditions -- say, ten of them. The probability that at least one individual would have at least one of those conditions is 1 - 0.9995^(1000*10) = 0.993 == ie, practically certain.

They really ought to teach basic probability theory in schools...

Not 1 in 2000

[RML]

The scientific goals of the 1000 Genomes Project are to produce a catalog of variants that are present at 1 percent or greater frequency in the human population across most of the genome, and down to 0.5 percent or lower within genes. A frequency of 0.5% is 1 in 200, not 1 in 2000. That's much easier to find with a thousand genomes, especially since they're not trying to figure out what the variations do, just that they exist.

Rare Conditons

[MassiveForces]

Finding diseases that eventuate in 1 in 2000 people with a genomic study of 1000 people is entirely possible... with one thousand people you have two thousand sets of genes. Since most genetic diseases are caused by two of the same recessive alleles (usually resulting from broken genes) in a single haplotype there would be lots of carriers; those with a single disease allele that could be spotted as a major deletion relative to the genomic reference sequence.