DNA Fingerprinting

Barbara Greene barbgrn at crl.com
Sun Aug 7 22:02:31 EST 1994


: Extraordinarily interesting dialog, you two! Thanks for taking the time. 
	I am a physicist, not an expert in your field, but have a kind of
a dumb question. 
	Is it not the results of the procedures one looks at? The
particular segments of dna are finally spread out in a film and it is the
presence or absence of various dna segments that comprises the unique
"fingerprint"? (And, naturally, statistical probability of having all vs
some of marker segments? No 2 people the same within x% probability?)
	In my field, if we bombard a helium or hydrogen target, the
resultant pieces are the same whether we do it at CERN or SLAC or LBL,
(more or less, forget quarks etc. for a minute). Does not matter who does
the work or how it is done (Bevatron, Linear Accelerator). 
	Can not 2 experts in the field look at the same result and agree -
if it is reasonably clear - on what it means? 
	Then, are not the issues that will be raised: contamination of
samples, statistical accuracy (faint, smudged, drifted results), the
statistical accuracy of the conclusions (only 1 chance in 1 milion that
this sample is NOT the same as this other sample, therefore from same
person), legal admissibility, chain of custody? 
	It's going to be fun watching them explain this on tv in little
sound bites! Waiting for a bunch of books on "DNA for the Complete
Idiot"... 
	Apparently the defense has 2 dna teams - one to prove the whole
technology is inaccurate (if it points to OJ), and another to prove the
technology is entirely accurate and dependable (if it points the other
way.)
	This is Law, not Science.




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