Overview
Statistical interpretation, Databases, QA, Challenges
- What might be some of the advantages and disadvantages of combining population databases (i.e., having a universal or mixed ethnicity database)? (2 points)
- What are some difficulties with low copy number DNA analysis? What kinds of checks and balances can a laboratory employ to ensure reliability of DNA profiles coming from low amounts of DNA template? (5 points)
- What are the benefits of using a mixture classification scheme as outlined in DNA Box 14.1? What would be the advantages of using software for deciphering mixture components? Justify your answers (5 points)
- You are a forensic biologist at Miami Dade Crime lab. You received a blood sample from a murder crime scene. The serology unit determined that this sample was not from the victim because the blood type is A+ and the victim was O-. You extracted the DNA from this sample and determined the STR profile. You can see here:
Later on, the detective sent you two reference samples from two suspects. You extracted the DNA from each sample and determined the STR profiles:
Without making any calculations, observe and record the following for each profile:
Observation A) Number heterozygous loci on each profile
Observation B) Most likely biological sex of donor from each profile
Observation C) Single-source or mixture classification for each profile
Record the alleles found at each locus for each of the three profiles and using the “Allele Frequency Table” on the last page of this assignment, create 3 tables similar to Table 11.3 from “1 – Statistical Interpretation” (one table for each profile).
What does a random match probability tell you?
What is the likelihood ratio for each Suspect’s profile? In your answer, clearly write down what the “prosecution hypothesis” and “defense hypothesis” is for each Suspect’s profile, and provide an example of calculation of likelihood ratio for the D3 locus of each Suspect A and Suspect B profile (show frequency values used for the calculation).
If asked in court to provide 100% certainty that one of the suspects was the perpetrator, would you be able to provide such answer? Explain your answer.