Mitochondrial DNA (mtDNA)

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Mitochondrial DNA (mtDNA)

• Two kinds of DNA Mitochondrial and Nuclear DNA

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Mitochondrial DNA (mtDNA)

• mtDNA molecules are present in hundreds or even
  thousand copies of cells
• In Nuclear DNA only two copies of the DNA
  fingerprint are present
• Used by Disease Detectives for origin and
  migration of epidemics

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DNA Sample

• Genomic DNA is taken from the sample
• Tooth
• Blood
• Hair

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Creating the Sample

• A PCR (polymerase chain reaction) is used to
  amplify or replicate sections
• PCR adds or adheres to the end of the sample
• An amplified PCR product is read by a laser

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Sample Comparison

• Two DNA forensic scientists compare the sample
• Compared to a Known sample of blood or saliva

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mtDNA as Evidence Disadvantages

• Known Sample and PCR Replicated sample must be
  done in different lab areas
• Cross contamination is a consideration
• Unknown is always processed first
• This prevents lab contamination from Known

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mtDNA as Evidence Disadvantages

• Rigorous
• Time Consuming
• Expensive
• Requires Experience to investigate results

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mtDNA as Evidence

• Only 4800 mtDNA Sequences
• Only a 95-98 confidence level that a match is
  correct
• Nuclear DNA is one in 5 billion!

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mtDNA as Evidence Advantages

• Nuclear DNA cannot process a hair sample without
  a follicle, mtDNA can
• Degraded samples (High acidity, temperature or
  humidity)

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mtDNA as Evidence Advantages

• Can be Used when all other tests fail
• Allele Chains are maternal
• If no genetic material sample is available, get a
  sample from the mother

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Case Law

• People v Morganti(1996)43 Ca 4TH 643
• People v Reilly (1987) 196 Ca 3d 1127

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Exclusion

• Two or more nucleotide differences between known
  and sample

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Inconclusive

• 1 Difference between known and sample

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Cannot Exclude

• Known and sample have common length variant or
  common base at each position
• People v Scott Peterson
• Stanislaus County no.1056770

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Mitochondrial DNA (mtDNA)

• Which type of DNA sampling and testing is used
  for Cold Hit investigation?