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Biotech / Medical : Celera Genomics (CRA) -- Ignore unavailable to you. Want to Upgrade?

To: gao seng who wrote (314)	5/8/2000 11:12:00 PM
From: allen menglin chen	Respond to of 746

I found Barron45_1999's YHOO posts valuable as well. Here is some of his good ones: On determining an individuals variation by: barron45_1999 5/8/00 10:09 pm Msg: 16806 of 16810 It would be outrageously inefficient to sequence every individual. Most of the functional sequence is identical (or equivalent) in every individual. [[Equivalent: because of the redundancy of the genetic code, the same amino acid can be coded for by as many as six different codons (strings of three "letters" (A,C, G or T)) So some variations in sequence will lead to exactly the same proteins.]] Out of 3,000,000,000 letters only about 300,000 in genes will be variable between individuals and only a small percentage of that will be in coding sequence. So all we really need to know to determine an individuals genetic DIFFERENCES is a few hundred thousand letters, not the whole 3 Billion. First the sites of variations have to be determined and the significance of the possible different alleles (variations) at each site. (Establishing the SNP database). Then we can make "gene chips", each one of which can simultaneously check for tens of thousands of variations. (Not all the details have been worked out but we know enough to know that it can be done). So ultimately what will happen (but it will be awhile) is that a drop or two of blood on each of a small number of gene chips will determine each patients genetic variations which will then be entered into his/her database. Such a process will be many orders of magnitude more efficient that actually sequenceing an individual There will be no need to sequence all of the "consensus" sequence (sites where all humans have the same or equivalent sequence), all that is necessary is to determine the differences. NOTE: The following is an ANALOGY and is NOT meant to be taken literally(so don't panic, sequenceman!): In ASTRONOMY (not genetics, it's an ANALOGY, sequenceman!) there is a tool called a "blink comparitor". This is used to rapidly and efficiently find comets from among the vast array of stars. Examining each individual point on a star photo and checking to see if it was a comet would be so time consumeing that it just could not be done. But a blink comparator flashes back and forth between two photos of the same peice of sky taken at slightly different intervals. Because the comet moves and the stars are fixed, as the images replace each other, a comet appears to jump back and forth and is thus readily distinguishable from the rest. An ANALOGY to that approach is what will be used to locate SNP's. The chips will be mass produced and thus fairly inexpensive. So determining an individuals profile will not cost tens of thousands of dollars. Probably somewhere in the hundreds. Most of the fees will come from using the database that intreprets the meaing of the SNP's for various things: what drugs will/won't be effective for a particular conditon, what diseases/envrionmental conditions/whatever will an individual be/not be susceptible to, what will/won't cause an adverse reaction, etc. etc. etc. Welcome to the third millennium messages.yahoo.com He is talking about gene chips -- AFFX is the next winner.