DNA Databases
Another point to mention is databases. There has been discussion about creating national databases of everyone's DNA type. That way, when a rape is committed, there's no need to find a suspect. You take the semen sample and get its DNA pattern, and compare it to a database of everyone's DNA pattern and find out whose it was. There are many people who feel understandably uncomfortable about such a national database. So legislatures have instead decided in some states to set these up, not for all citizens, but for only those convicted of, say, sex offenses, and other states for those convicted of any felony.
There is a lively controversy over what sorts of databases should be set up and there are those who say - why should it matter? Why should you care if you're in a database? After all, if you're innocent, there's no chance the technology will do you any harm. Well, even if standards are being discussed and looked at, and I'm an optimist, I feel that the standards are being worked out well. I think the Academy's report and many other steps are doing a great job of putting this on the most rigorous footing possible.
Polymerase Chain Reactions
New developments occur at a dizzying pace. For example, Polymerase Chain Reaction is a marvelous technology to amplify DNA. It allows you to take a specific region of DNA on the chromosome, and by using little black primers here and copying back and forth, back and forth, just the particular region you want to copy, making two, then four, then eight, then sixteen, up to millions of copies of a particular region, and so in principle it is possible to start from the DNA of a single cell and get enough DNA to analyze it. That makes it possible not just to analyze blood stains of the sort that were seen before in which you could get one microgram, one millionth of a microgram of DNA, or semen swabs from a rape, some of which give you enough to analyze by standard techniques, but in fact even shed hair has enough DNA at its root. A urine sample, saliva sample, will have enough DNA in most cases. It's possible that by licking an envelope you deposit enough DNA to trace from the seal of the envelope.
Obviously, a technology that is so powerful and that is that sensitive must be used even more carefully, since you can imagine that if I sneeze on something, my DNA is there, too. And so there is tremendous need to avoid contamination. Proficiency tests have to be put in place to guarantee that laboratory practice is up to that. These are questions under debate.
  
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Winding Your Way Through DNA Resource Book Index
