DNA fingerprinting in the twilight zone.

It the close of the last decade, Science announced its intention to counteract the symbolization of years by people by naming a "Molecule of the Year." Nor is this irony. Science's editor, Daniel E. Koshland, Jr., asserts that "our present standard of living depends on" science and technology, and that describing personalities" obscures the "fundamental causes of progress.... The challenge to science is to generate new discoveries. The challenge to society is to use those discoveries for the betterment of all." Although taking some of the spotlight off celebrities is constructive, the implicit claim that science is or should be divorced from society cannot be taken seriously, as a brief discussion of some of society's attempted uses of Science's 1989 "Molecule of the Year" illustrates. The award for 1989 went to "the DNA polymerase molecule and to the technique called polyrnerase chain reaction, PCR...." PCR is a technique for amplifying small quantities of genetic material into "large quantities of accessible, identifiable, and analyzable material" that can be used to help diagnose diseases and detect pathogens. But, as Science explains, one of the most societally important uses of this technology will be in the area of identifying individuals from small DNA samples: DNA samples in trace materials (semen, blood, hairs) found at the scene of a crime have been compared with DNA samples from crime suspects; both acquittals and convictions have resulted from such comparisons. Missing persons have also been positively identified through PCR-based comparisons. The resolution of paternity cases has been aided by comparing DNA from a child with that of the alleged father. This description is of interest because fewer than 5 percent of the approximately 1,000 criminal cases and 3,000 paternity cases in the United States in which DNA technology has been used have involved PCR amplification (almost all em lo the less exacting techniques described below); only one of the three major laboratories doing "DNA fingerprinting" uses PCR; and the example is put forward at a time when DNA matching in criminal cases is under intense attack because the scientific protocols for its use have not been well defined by scientists themselves. DNA fingerprinting, then, provides a useful example for exploring the relationship between science and society. DNA Fingerprinting A suspect may be placed at the scene of the crime in a number of ways. The most common is by an eyewitness. But eyewitnesses are notoriously unreliable, and most prosecutors prefer to have eyewitness testimony supplemented by physical evidence such as fingerprints or footprints. In violent crimes like rape and murder, the perpetrator may leave his sperm or blood behind, or carry away some of the victim's blood on his person. Using ABO blood groups, individuals can be excluded as suspects. Using DNA typing, however, it has been suggested that suspects can be conclusively identified as the source of blood or sperm. This type of identification has been hyped by law enforcement officials as the ultimate law enforcement tool, and its first use to help solve a murder case is graphically chronicled in Joseph Wambaugh's current bestseller, The Blooding. A California Department of Justice official predicts that "in a few years, a crime-scene sample will tell a suspect's race, eye color, hair color and even his build." Others see DNA samples as eventually being fed into a computer that will decode them and produce "an image like the kind our police artists do now."3 So entrenched had the patina of scientific "fact" surrounding DNA fingerprinting become that although the technique has been used in the courtroom since 1986, it was not until 1989 that criminal defense attorneys even attempted to challenge its validity. These initial challenges have been so successful that effective use of the technology may have been set back years. How the Test Works The standard method of DNA fingerprinting utilizes the same restriction fragment length polymorphism analysis (RFLP analysis) used in genetic testing and screening. …