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A crime scene sample was analyzed based on the four STRs described below. The suspect's cheek cell swab showed the same STRs as the crime scene sample. What is the probability that another person in the suspect's population has the same pattern of these alleles? STR1: The readout has a single tall peak. The prevalence of this allele in the suspect's population group is 0.65 STR2: The readout has two shorter peaks. The prevalence of allele 1 is 0.75 and of allele 2 is 0.15 In the suspect's population group. STR3: The readout has two shorter peaks. The prevalence of allele 1 is 0.66 and of allele 2 is 0.20 in the suspect's population group. STR4: The readout has a single tall peak. The prevalence of this allele in the suspect's population group is 0.25.

Multiple Choice
a. 16025
b. 1/635
c. 162
d. 116

User Myron Slaw
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7.5k points

1 Answer

4 votes

Final answer:

To calculate the probability that another individual in the population has the same STR profile, we multiply the genotype frequencies of each independently inherited STR locus. As we don't have a specific answer to match from the options given, the calculation would simply involve multiplying the allele frequencies provided for each STR, considering heterozygosity where appropriate.

Step-by-step explanation:

In the context of population genetics, determining the probability that another person in the suspect's population has the same pattern of Short Tandem Repeats (STRs) involves calculating the combined frequency of these alleles. This relies on understanding allele frequencies and how they can be used to predict genotype frequencies within a gene pool. Given the allele frequencies for the four STRs, we calculate the probability for each STR independently and multiply them together because they are inherited independently.

For STR1 (0.65), STR2 (0.75 for allele 1 and 0.15 for allele 2), STR3 (0.66 for allele 1 and 0.20 for allele 2), and STR4 (0.25), we assume the two alleles at STR2 and STR3 are heterozygous, and thus the individual frequencies are multiplied by 2. Therefore, the probability is calculated as follows:

  • STR1: 0.65
  • STR2: 2 * 0.75 * 0.15
  • STR3: 2 * 0.66 * 0.20
  • STR4: 0.25

The combined probability of an individual having this specific set of STRs is the product of these probabilities. However, as the exact answer is not provided, we cannot accurately give the probability. One would need to multiply those individual probabilities accordingly to find the probability for the entire STR profile.

User Niton
by
8.0k points
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