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Week 9 - DNA IV
Kinship and Victim Identification
Question | Answer |
---|---|
What sort of cases involve kinship? | Paternity testing, missing persons, mass disasters, immigration, criminal cases where relatives might be involved. |
What are obligate paternal alleles? | Only uses the father in kinship analysis. |
What is the paternity index? | Ratio of two conditional probabilities; numerator assumes paternity, denominator assumes a random man was the father. PI of 100 or greater= good indication it is the father. |
What is exclusion probability? | The combined frequency of all genotypes that would be excluded if the pedigree relationships were true assuming HWE. |
What is a germ line mutation? | It occurs in either the males sperm or female's egg cell and is passed onto the zygote. |
Matches between parents vs offspring | An exact match may not occur between parents and offspring due to mutations. Some alleles have a higher mutation rate. 1-2 inconsistencies between offspring and father is normal. |
How often do mutations occur? | Approximately 1-3 mutations for every 1000 alleles transferred (meioses) |
Which parent usually has a higher rate of mutation and why? | Paternal has higher rate of mutation because sperm goes through more meiotic divisions, more chances for mutations to occur. |
Which loci have the highest levels of mutation and why? | VWA, FGA and D18S51. Because they are the largest and longer alleles mutate more often than smaller alleles. |
Which loci have the lowest levels of mutation? | TH01, TPOX and D16S539 because they are the smallest alleles (less repeats) |
Why do certain alleles mutate more often than others? | -Longer alleles mutate more often than shorter alleles (base pairs) -Paternal alleles mutate more frequently than maternal alleles -Unequal sensitivity to mutations in certain alleles (some prone to mutation, some resistant) |
Why do certain alleles mutate more often than others? continued | -Not all alleles undergo mutation with equal frequency |
Why is mitochondrial DNA (maternal) not as powerful in reference sampling? | More than one person can have the same haplotype, not as powerful because it will be common among siblings. |
What are a few problems you will run into in Disaster Victim Identification? | -Contaminators -A lot of mixed samples -Decreased power of discrimination -Degraded samples |
What are some things you could do to still get a profile? | - Mini STR's -SNP's -Mitochondrial DNA -Y STR's |
What does KADAP stand for and what is it? | Kinship and Data Analysis Panel -Panel of experts formed after 9/11 -Mission was to aid in reviewing data and provide guidance and recommendations regarding the statistic thresholds -George Carmody, CU |
What is a Mini STR? | -It uses a smaller PCR product size -Less than 200 BP -Contains same information as a traditional STR -Useful for typing degraded DNA samples |
Who was Baby 81? | Baby 81 was found alone after the Indian ocean earthquake occurred. The parents had no proof of birth as it had been washed away and further filed for DNA testing to claim him. DNA tests confirmed parents and were allowed to take him home. |
What kind of challenges do you face with mass graves? | Degraded samples, mixtures, inhibitors |
What is the I.C.M.P? | International Commission on Missing Persons |
What is the purpose of the I.C.M.P? | Established to support the Dayton Peace agreement which ended the Bosnian war. It's primary role is to ensure the cooperation of gov's in locating and identifying missing persons in the wake of conflict or natural disasters. |
What is deep ancestry? | "Genetic Geography" (group comparisons) -Looking for relationships from >1000 years ago -Offers a big picture view of our past -Involves testing with lower resolution genetic markers (Y-SNP's) to determine haplogroups |
What is genetic genealogy? | Individual comparisons -Looking for relationships from <1000 years ago -Tries to provide link between related people -Involves testing with higher resolution genetic markers (Y-STR's) to determine haplotypes |