DNA Typing

Within the last decade, DNA (deoxyribonucleic acid) typing has provided scientists, police, investigators and attorneys with very valuable identification information. It has become the standard method for human identification. As research on the maps of chromosomes continues and new discoveries are made, the level of characterization of the human genome is reaching dramatic new levels. One of the most spectacular of the more recent scientific advancements has been the development of polymerase chain reaction (PCR) DNA typing.

PCR-based DNA typing is a very powerful technique for the analysis of biological evidence. PCR methods enable scientists to replicate a small amount of DNA obtained from minute stains millions of times. The amplified portion represents a particular variable region of the DNA, which may be analyzed by electrophoresis, a method used for separat-ing molecules according their size and electrical charge.

PCR has many advantages over traditional methods, such as restriction fragment length polymorphism (RFLP) analysis, which include:

• The ability to analyze samples that are degraded by environmental factors such as heat, UV light, humidity and chemicals.
  
• The ability to analyze samples that have been eiposed to microbial contamination.
  
• A short preparation and analysis time of only a few days (versus weeks for RFLP).
  
• The ability to analyze "difficult" samples such as cigarette butts, envelope flaps, semen, hair, and bone.
  
• Powerful discrimination potential.

PCR methods have been extensively validated by the scientific community and have a history of acceptance by courts throughout the country. Population studies have demonstrated that, in combination, these powerful tests can provide discrimination potentials in excess of 99.9%

Forensic Analytical provides high quality PCR-based DNA typing services and court qualified expert testimony to both the criminal and civil legal communities. Forensic Analytical's skilled experts are committed to accurate, reliable and timely results. Currently available PCR tests include the DQA1, Polymarker, and short tandem repeat (STR) loci.

Short Tandem Repeats (STRs) and Automated DNA Typing
Forensic Analytical has remained committed to being a technology leader and employing the most advanced techniques in DNA typing. Among the most recent advancements in the field of DNA typing is the ability to simultaneously analyze multiple genetic markers referred to as short tandem repeats (STRs). The analysis of multiple STR loci can increase discrimination potentials to values formerly achieved only by RFLP analysis. Analysis of STR loci is facilitated by the ability to label PCR products with fluorescent dyes which may be detected with capillary electrophoresis instruments such as the PE Applied Biosystems Prism 310 Genetic Analyzer. The sophisticated instrumentation and automation aids in the interpretation of analytical data and reduces the possibility of errors due to human handling. The AmpFl STR Profiler Plus kit utilized by Forensic Analytical affords the ability to simultaneously type nine STR loci and the sex marker, amelogenin. Specific markers include:

• D3S1358
  
• D13S317
  
• VWA
  
• D18S51
  
• D8S1179
  
• D5S818
  
• FGA
  
• D7S820
  
• D21S11
  
• Amelogenin

Forensic Analytical, 3777 Deport Road Suite 409, Hayward, CA 94545. Tel: 800-827-3274; Fax: 510-887-4218.