By Robert M. Frederickson
June 14, 2005 | It has become hard to tune in to one’s favorite crime show on television these days without running across an odd-looking, eccentric character depicting the “scientist,” using the latest technologies to help identify either the victim or perpetrator of some gruesome crime. Of course, the reality is that the use of modern forensic science has indeed benefited from the tremendous advances in genomic technologies, and the genomics industry has come forward with tools that can be used successfully by even the most conventional-looking laboratory worker.
A good example recently appeared not on the latest episode of CSI: Miami, but in fact, on the local news in the San Francisco Bay area. According to a story in May on KGO-TV, an ABC affiliate in San Francisco, a murder in the Mammoth Lakes area in California’s southern Sierras has become a test case for the use of genomics in forensic science and could become the model for the future of genomic crime fighting. In May 2003, a body was found in a shallow grave at a campground. The remains were sent to the San Francisco Medical Examiner’s office, which determined that the victim was a woman of Southeast Asian descent. However, the focus of the investigation changed after a sample was sent to DNAPrint Genomics of Sarasota, Florida, as use of their DNAWITNESS technology determined that the victim was actually of Native-American descent. Using new techniques from DNAPrint and other scientific laboratories, authorities were able to build a sketch of the woman that matched an artist’s sketch drawn from a description of a woman who visited the campground in the fall of 2002.
DNAWITNESS 2.0 is used by law enforcement agencies to determine the likely genetic heritage of DNA samples obtained from crime scenes — thereby narrowing the potential pool of suspects or victims. Earlier forensic DNA products acted more like a fingerprint and could only be used to match DNA specimens — which is of little use without a set of likely suspects from whom DNA can be obtained. Instead, DNAWITNESS provides the percentage of genetic makeup of an individual from four possible groups: Sub-Saharan African, Native American, East Asian, and Indo-European.
According to Richard Gabriel, the company’s president and CEO, DNAPrint technology has impacted a number of high-profile murder investigations. A case in Concord, California, had targeted Hispanic- or Asian-descent gang members in a murder, based on eyewitness reports. However, it turned out that the perpetrator was actually Caucasian, based on the results from the DNAWITNESS assay.
DNAPrint technology makes use of ancestry informative markers (AIMs), which are particular single nucleotide polymorphisms (SNPs) identified in the human genome. The company has filed patent applications covering several key AIMs that they have linked to human disease, reactions to particular drugs, forensics, and human heredity and identity. They have verified these markers in high-throughput screens and have applied them for genome-screening applications. The AIMs are mapped using the proprietary mapping by admixture linkage disequilibrium (MALD) method. MALD allows known statistical data about population structure to be exploited to reduce substantially the number of SNPs analyzed — leading to more cost-effective analysis. Thus, by analysis of a limited number of SNPs in a particular sample, the company can assign likely genetic heritage.
Last August, the company unveiled the next generation of its genetic profiling package, DNAWITNESS 2.5. The new package included the RETINOME genetic test to predict eye color from a DNA sample, again based on the analysis of a select set of SNPs. Eye color has its genetic basis in a host of genes. RETINOME was developed from a genome screen of tens of thousands of SNPs in thousands of European subjects. The most recent blind validation test for 65 individuals of predominant (greater than 80 percent) European ancestry, between the ages of 10 and 60 years of age, showed greater than 97 percent accuracy.
Robert M. Frederickson is a biotech writer based in Seattle. E-mail: firstname.lastname@example.org.