miniPCR bio™ Electrophoresis Forensics Lab. Wrongfully Convicted? Instructor's and Student's Guide
Version: 1.1 - Release February 2022 - © 2022 by miniPCR bio™
Additional
Supports
P./30
STR location Genotype Genotype frequency
D2S441 11, 14 0.1544
D5S818 11, 12 0.2230
D7S820 7, 8 0.0054
D10S1248 13, 13 0.0764
D13S317 11, 12 0.1772
D16S539 8, 14 .00092
D18S51 20, 21 .00069
Table 2. Genotype frequencies for select STR locations
National Institute of Standards and Technology. "1036 Revised
U.S. Population" July 2017. Dataset. https://strbase.nist.gov/
NISTpop.htm. Accessed 7/29/2020.
In the previous questions, you focused on
a single STR location, but remember that
forensics scientists analyze many STR regions.
Table 2 shows an STR profile that contains
seven STR locations. In this table, the genotype
frequencies, like those you calculated in the
previous problems, have been calculated for you.
3. Based on the genotype frequencies in
Table 2:
A. For which STR location(s) does
this individual have a common
genotype shared by more than
20% of the population?
4. Imagine you are testing a crime scene DNA sample. While it is standard for forensic
scientists to examine at least 20 STR locations to create a DNA profile, this has not always
been the case.
A. Multiply the genotype frequencies in Table 2 to calculate the random match probability
for this STR profile using the product rule. Show your work.
B. For which STR location(s) does this individual have a genotype so rare that less than
0.1% of the population share it?
