About human DNA sequence identity - (Dec/04/2010 )

Hi all,


We are often told that the human genomes share 99% sequence identity and I am a little bit confused about such an "assumption".
How can we claim this finding while we never sequenced all human genomes in the world to know and compare their sequences and conclude results! So, how this high percentage of sequence identity was concluded for all people (i.e. ~ 6 billion humans)?!
How we could be sure that all people on earth have this high percentage of sequence identity?
Since the human genome was sequenced using the DNA of few individuals, and unless we sequence all human genomes in the world, how we could be sure that human beings share 99% sequence identity?

I am a little bit confused about this issue.
Does somebody has any clear idea ?

Thanks for any feedback

This sounds a lot like homework... so only some things to think about.

Conservation of genes and the number of people sequenced for some genes.

Recent study showing Japanese having different genome(I'm sure if you do a web search you'll find it).

bob1 on Sun Dec 5 22:12:30 2010 said:

No it is not! !

bob1 on Sun Dec 5 22:12:30 2010 said:

Does sequencing of some genes in number of people is enough to claim that humans (all people on earth) share 99% sequence identity? Without speaking about other genomes and other species (that we also claim having a high percentage of sequence identities with their genomes!)

bob1 on Sun Dec 5 22:12:30 2010 said:

So, this goes in the direction of my question, and my homework question is legitimate, isn't it?
Unless we sequence all genomes, claiming similarity betweens species or humans as high as 99% isn't an overstatement based on theoretical assumption only??

to be human you must share a certain set of genes. despite variations, such as snps, deletions and other mutations, the vast majority of bases in the gene sequences will be the same. certainly more than 99%.

I got this from wikipedia:

"The haploid human genome occupies a total of just over 3 billion DNA base pairs."

So, even if we are just 1% different from each other, 1% of 6 billion bp should be enough to accomodate known and to be discovered mutation in us...

How do we know that there are 6 billion people in the world when we never counted them all? How do we know that if you flip a coin enough times it will come up 50% heads and 50% tails? Statistics.

Yes, but to do good statistics, we have to sequence hundreds and hundreds of genomes!