Finish It Already

A blogger wonders why the human genome still isn't completely done.

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Sandra has raised a great

Sandra has raised a great point. She has also correctly identified significant development that has happened in DNA sequencing technologies in the past. However, sadly the sequencing technologies has developed only to make denovo sequencing harder. With new technologies, one can sequence faster only to create shorter random pieces of DNA needs to be put together to create the whole picture. Current technologies generate 50bp to 450 bp random sequences in length making it even harder to assemble this puzzle compared to older sequencing technologies which generated 1000 bp long strings. The missing regions in human genome may have been sequenced already but to determine and correctly place it in its correct place in the genome remains a bigger question.
To summarize, imagine yourself putting a puzzle together broken into 100,000 pieces and now imagine the same puzzle broken into 100,000,000 pieces.

I agree with that comment,

I agree with that comment, but this is somewhat ameliorated by the incredible drop in sequencing cost with the newer technologies. Capillary sequencing in high throughput costs about 50 cents per lane, generating about 700 nucleotides at quality Q20 or greater, so about $715 per million nucleotides. The newer technologies can generate sequence as cheaply as $1 per million nucleotides, so we can get much deeper coverage, even for much lower cost.

The seeming contradiction in wanting to "finish" the genomes of chimp and macaque versus finishing the human is simply in the definition of the word "finish". We now have random shotgun sequencing for several different humans, in aggregate comprising fantastically deep coverage of the human genome. No other genome of comparable size has anything close to as complete coverage and analysis as the human genome. The very few remaining gaps have not been closed because: (1) It is not simply a matter of sequencing, but instead is the resolution of vast tracts of repeated sequences. (2) The number and composition of these repeats is not very interesting scientifically and probably varies a lot among humans anyway. (3) The effort at understanding the variation among humans is much more interesting and important (see the fantastic work of Evan Eichler's group, for example) than obsessing about these gaps of trivial importance. In contrast, when people are talking of "finishing" the genomes of chimp and macaque and other organisms, they are speaking of further efforts at improving the quality of these draft genomes. No one even imagines that sufficient effort will be expended any time soon to get these anywhere close to the quality of the human genome sequence.