Exam 3 Start: Lecture 10

Question 1

What is evidence of mixture
(3)

Answer 1

• Too many alleles (at MORE than one locus)
• Peak imbalance (If shared, could result in higher peaks) (for A, if it is a mixture of M & F, X would be rlly big peak)
• Particularly high stutter (more if the other two are also present)

Question 2

How do you determine how many people are in a mixture?

Answer 2

You can only estimate based on the assumption that everyone has two alleles

Number of alleles / 2

Question 3

What is a possible way to tell out of four alleles which two belong to who
(Not “ironclad”)

Answer 3

Peak height = amount of i DNA
If two peaks are relatively same height, they could belong to the same person

This is because usually in mixtures there is a major and minor contributor, more of one person’s DNA in a mixture sample (ratio of contribution)

Question 4

What is it called when there is only one locus with three alleles present

Answer 4

Tri-allelic

Question 5

For exam, be able to look at an example mixture and known contributor to find the others (possible) alleles (2)

Answer 5

To do this check:
- presence (more conservative)
- peak height

Question 6

What is an issue with analyzing mixtures?

Answer 6

• Suspect might have an allele not found in the mixture (might even be below threshold)

Question 7

If suspect is not excluded, a common controversial step is to

Answer 7

Calculate 1- probability
CPI

Question 8

What are the three distinct patterns that can be seen in major/minor contributor mixtures? (Deconvoluted mixture) (In a perfect world lol)

Answer 8

• All 3 tall
• One tall two short
• 3 different sizes

Question 9

What would produce a pattern of 3 all same height?

Answer 9

If the major contributor is heterozygous and minor is homo

Question 10

What would produce a pattern of 1 tall and 2 short?

Answer 10

Major contributor is homozygous and hetero is minor

Question 11

What would produce a pattern of all different heights (tall, medium, short)

Answer 11

Hoth heterozygous, one of those alleles is shared (the tallest one)

Question 12

What are the two solutions for ID mixtures?

Answer 12

• Sophisticated software for conventional STR profiles
• massively parallel sequencing tech (NGS) (NOT USED OR VALIDATED CURRENTLY)