what is mitochondrial dna (mtdna)?
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
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