Download - What is Mitochondrial DNA (mtDNA)?
What is Mitochondrial DNA (mtDNA)?
• Maternally inherited– Every individual in the same maternal lineage should have
the same mtDNA sequence• More sensitive than nuclear DNA– Each cell contains 1000’s of copies of mtDNA vs. 1 copy
of nuclear DNA• mtDNA is analyzed by sequencing– Hypervariable I (HV1) and Hypervariable II (HV2) regions
- look for actual A,G,T,C sequence
When to use mtDNA testing
Hair samples with no or insufficient roots Cases where nuclear DNA analysis does not
result in sufficient information for a conclusion
Identity situations where there the only reference available is a maternal relative
**mtDNA is not good in cases of mixtures
mtDNA Report
Why would a Public Defender pursue DNA testing?
• Results don’t have to be incriminating They can also corroborate a story
• Questions about “no results” from evidence that you think should yield a result
• Questions about mixtures
When to seek a DNA test vs. DNA review
• Re-test– Results of first test
inconsistent with what is expected• No results were obtained
– Mixture• Lab can’t include or
exclude your client
• Review– No results (no chart) listed
in report-only conclusions–Mixture- Is your client
really included?– If you are confused by the
results
Listen to your client
What to ask for Re: Discovery
• Copy of complete case file (Including all raw data)– Serology– DNA
• Copy of Protocols– Standard Operating Procedures (SOP)– Quality Assurance/Quality Control (QA/QC)
• Database information (Frequency tables)
At a Minimum
Additional Items
What to ask for Re: Discovery
• Quality control records– Kits used– Critical Reagents
• Records of Proficiency Tests (each analyst)• Copies of Audit documents• Validation Information • Accreditation Information
What to look for in an expert
• Aspects to consider when picking an expert and/or laboratory
– Price– Turn-around time– Accredited laboratory– Experts who provide service both Defense
and those other guys (more credibility)
Thank You
Meghan E. Clement
LabCorp Forensic Identity Department