SNPs Over STRs in Familial Testing to Minimize Errors

Professor Advocates for SNPs Over STRs in Familial Testing to Minimize Errors

Familial testing has gained prominence in forensic scienceDiscover the fascinating field of Forensic Science, the application of scientific principles to legal matters. This post delves into its many disciplines, from DNA analysis to crime scene investigation, its importance in the justice system, Read Full Definition, particularly after its success in high-profile cases like the Golden State Killer. However, Jianye Ge, associate director of the Center for Human Identification at The University of North Texas Health Science Center, highlights significant limitations of Short Tandem RepeatA short tandem repeat is a microsatellite with repeat units that are 2 to 7 base pairs in length, with the number of repeats varying among individuals, making STRs effective for human identification purposes Read Full Definition (STR) technology. In a study published in PLOS Genetics, Ge demonstrates that Single Nucleotide PolymorphismsA single nucleotide polymorphism, or SNP (pronounced "snip"), is a variation at a single position in a DNA sequence among individuals. Read Full Definition (SNPs) offer greater accuracyIn scientific and measurement contexts, "accuracy" refers to the degree of proximity or closeness between a measured value and the true or actual value of the measured quantity. Accuracy indicates how well a measurement reflects Read Full Definition, urging the forensic community to adopt high-density SNP panels for more reliable results.

The Rise of Familial Testing in Forensic Science

Familial testing has become a crucial tool in forensic science, aiding in solving numerous criminal cases and identifying missing persons. The method’s popularity surged notably after the Golden State Killer case. Jianye Ge estimates that familial testing has been used in over 15 million criminal cases and missing persons identifications, showcasing its widespread application and success.

STR Technology: Current Standard but With Limitations

Understanding STRs

Short Tandem Repeats (STRs) have been the standard in DNA profiling DNA profiling, also known as DNA fingerprinting, is a significant technique in forensic science that identifies individual's unique DNA patterns for various purposes such as establishing familial relationships or tracing genealogical roots. The technique, which Read Full Definition due to their high power of discrimination. However, Ge’s study reveals that this technology has notable limitations, particularly in familial relationship testing.

Error Rates in STR-Based Testing

Ge and his colleagues used a 15 autosomal marker kit and calculated false interpretation rates for different familial relationships:

• Trio cases: 0.058%
• Parent-child cases: 1.14%
• Full-sibling cases: 20.82%

Even with kits containing 21 STRs, false rates were significantly high, indicating inherent issues with STR technology.

SNP Technology: A More Reliable Alternative

Advantages of SNPs

Single Nucleotide Polymorphisms (SNPs) offer a higher cumulative power of discrimination despite having lower discrimination power per locusA locus is the precise position of a gene on a chromosome. Different alleles of the same gene occupy the same locus. Read Full Definition compared to STRs. High-density SNP panels can test hundreds of thousands to millions of SNPs, significantly reducing error rates in familial testing.

Recommendations for Transition

Ge recommends forensic labs to:

1. Investigate high-density SNP technologies.
2. Perform cost-benefit analyses for in-house implementation or outsourcing.
3. Develop standard workflows and software tools.
4. Educate users on SNP technology’s strengths and limitations.
5. Validate SNP-based methods to meet scientific and legal standards.

The Path Forward

Ge emphasizes the importance of validationValidation, often referred to as method validation, is a crucial process in the laboratory when introducing a new machine, technology, or analytical technique. It involves a series of systematic steps and assessments to ensure that Read Full Definition to ensure that SNP-based technologies can withstand scientific scrutiny and legal admissibility standards, akin to current forensic DNADNA, or Deoxyribonucleic Acid, is the genetic material found in cells, composed of a double helix structure. It serves as the genetic blueprint for all living organisms. Read Full Definition testing systems. By adopting SNP panels, the forensic community can enhance the accuracy and reliability of familial relationship testing, reducing the likelihood of false interpretations.

Summary

Transitioning from STR to SNP technology can significantly improve the effectiveness of familial testing in forensic science. Jianye Ge’s research underscores the limitations of STRs and advocates for adopting high-density SNP panels to minimize errors. Forensic labs are encouraged to explore and validate SNP-based methods to ensure more accurate and reliable results.

How do you think adopting high-density SNP panels will impact the accuracy and reliability of familial testing in forensic science? Share your thoughts and join the discussion!

Paper Reference: Ge J, Budowle B (2020) How many familial relationship testing results could be wrong? PLoS Genet 16(8): e1008929. https://doi.org/10.1371/journal.pgen.1008929