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| Science & Technology |
| DNA ID May Not Be As Infallible As Imagined |
| 2008-07-21 |
| A discovery leads to questions about whether the odds of people sharing genetic profiles are sometimes higher than portrayed. Calling the finding meaningless, the FBI has sought to block such inquiry. State crime lab analyst Kathryn Troyer was running tests on Arizona's DNA database when she stumbled across two felons with remarkably similar genetic profiles. The men matched at nine of the 13 locations on chromosomes, or loci, commonly used to distinguish people. The FBI estimated the odds of unrelated people sharing those genetic markers to be as remote as 1 in 113 billion. But the mug shots of the two felons suggested that they were not related: One was black, the other white. In the years after her 2001 discovery, Troyer found dozens of similar matches -- each seeming to defy impossible odds. As word spread, these findings by a little-known lab worker raised questions about the accuracy of the FBI's DNA statistics and ignited a legal fight over whether the nation's genetic databases ought to be opened to wider scrutiny. The FBI laboratory, which administers the national DNA database system, tried to stop distribution of Troyer's results and began an aggressive behind-the-scenes campaign to block similar searches elsewhere, even those ordered by courts, a Times investigation found. At stake is the credibility of the compelling odds often cited in DNA cases, which can suggest an all but certain link between a suspect and a crime scene. When DNA from such clues as blood or skin cells matches a suspect's genetic profile, it can seal his fate with a jury, even in the absence of other evidence. As questions arise about the reliability of ballistic, bite-mark and even fingerprint analysis, genetic evidence has emerged as the forensic gold standard, often portrayed in courtrooms as unassailable. But DNA "matches" are not always what they appear to be. Although a person's genetic makeup is unique, his genetic profile -- just a tiny sliver of the full genome -- may not be. Siblings often share genetic markers at several locations, and even unrelated people can share some by coincidence. No one knows precisely how rare DNA profiles are. The odds presented in court are the FBI's best estimates. The Arizona search was, in effect, the first test of those estimates in a large state database, and the results were surprising, even to some experts. Defense attorneys seized on the Arizona discoveries as evidence that genetic profiles match more often than the official statistics imply -- and are far from unique, as the FBI has sometimes suggested... |
| Posted by:Anonymoose |
| #12 Oh, oh, somebody been using conserved regions for DNA fingerprinting. |
| Posted by: g(r)omgoru 2008-07-21 21:25 |
| #11 Is she related to Verne? |
| Posted by: Nimble Spemble 2008-07-21 15:59 |
| #10 "The beauty of Science is that it is continuously revising itself." Except for Gerbil Wormening, AHM. AlBore says that's settled |
| Posted by: Barbara Skolaut 2008-07-21 14:53 |
| #9 As I recall, DNA is generally used to exclude suspects, not to include them. |
| Posted by: Iblis 2008-07-21 14:07 |
| #8 I would suspect that this is a similar problem to the partial fingerprint ruling from not too long ago. That is, the smaller number of points used, relative to the total data field, the higher chance of inaccuracy. This makes all the sense in the world if you compare it to CAD software. Back when it was primitive, it used few data points to connect the lines, so round objects had a boxy or beveled appearance. But as the software got better, with more data points, rounded objects became smoother. Eventually, so many data points are used that round looks round. I'm sure there will be more on this later. |
| Posted by: Anonymoose 2008-07-21 14:02 |
| #7 The FBI should stay out of this and let Science take its course. One of the basic truths of DNA and genetics is there is still a LOT we don't understand. The beauty of Science is that it is continuously revising itself. Better to explore the possibility that she is correct than to find lingering questions casting doubt on DNA evidence in the future. |
| Posted by: AllahHateMe 2008-07-21 13:28 |
| #6 The good news is that science is testable. If Ms. Troyer is correct her work can be replicated by other labs. Perhaps there is something to this, perhaps not. But even if the FBI is unhappy, the truth about genetic profiling will come out. |
| Posted by: Steve White 2008-07-21 12:56 |
| #5 I have no detailed knowledge of the tech but a 9 of 13 match does not seem to equate to a match to me. 13 of 13 would be a match. It seems to me that some lawyers are looking for an out for their clients. I would appreciate if someone with real knowledge of the process would comment. |
| Posted by: tipover 2008-07-21 11:24 |
| #4 Or, people with criminal tendencies share common DNA profile markers. That'll open a can of 'we can't go there' from the usual crowd. Reviving the old notion of 'bad blood' isn't PC. |
| Posted by: Procopius2k 2008-07-21 11:08 |
| #3 unrelated people sharing those genetic markers to be as remote as 1 in 113 billion And thats their error. In any population most people will be related to most other people. |
| Posted by: phil_b 2008-07-21 10:37 |
| #2 Apparently, inbreeding was rampant in Arizona. Wait until they check the Ozarks and Appalachians. |
| Posted by: Woozle Unusosing8053 2008-07-21 10:22 |
| #1 Damn right! |
| Posted by: O.J. Simpson 2008-07-21 10:06 |