Lec 5: STR limitations and SNPs

Technique and Amplification Errors

Probably not; early discussions focused on RFLP, now PCR

Risks of Sample Contamination

Very significant

Stages of Sample Contamination

All of the above (During sample collection, storage, analysis)

Objectivity of Band Recognition

A recent study suggests this can be subjective, at least in part

Influence on Band Pattern Interpretation

The investigator's knowledge of the sample

Likelihood of ‘Random’ Matches

Still very contentious

Robustness of Statistics on Matching

Somewhat robust, but contentious

Factors Contributing to Uncertainty in DNA Matches

All of the above (Different allele frequencies, variation in techniques, subjective interpretation)

Overall Limitations of DNA Typing

No, DNA typing is no more infallible than any other forensic analysis

Technical Limitations of STR Technology

Capillary sequencers are old technology, STR relies on DNA of length ≈ 500 bp, Difficult to amplify degraded DNA

Summary of Limitations

Forensic DNA testing is as subjective and fallible as other forensic analyses