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

Clemenm@LabCorp.com