# DNA Profile Interpretation

- Created by: AAntonianannetti
- Created on: 10-05-19 13:07

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- DNA Profile Interpretation
- Once a DNA profile match has been made, the significance of the match has to be estimated.
- Need to estimate the frequency of a DNA profile
- Need experience to reliably interpret DNA profiles, especially those that are degraded and have low levels of DNA
- Requires knowledge of population genetics and some statistical analysis of data
- Essential to understand where the profile comes from in order to assess the strength of a match
- A population can be described as a group of people sharing common ancestry.
- it is not possible to estimate allele frequencies from the whole population as this would require testing everybody
- Population databases therefore represent a subset of the population

- it is not possible to estimate allele frequencies from the whole population as this would require testing everybody

- Estimate how rare or common a DNA profile may be

- When a match is found, the probability that a second copy of the DNA profile will be present in a certain population is determined.
- Random Match Probability
- Likelihood Ratio

- Need to estimate the frequency of a DNA profile
- Hardy-Weinberg Equilibrium
- If a random person is picked from the population, we can calculate the probability that they will have a particular genotype
- Condition that occurs when the frequency of alleles in a particular gene pool remains constant over time
- Equation = p2 + 2pq + q2 = 1
- P = Dominant (AA)
- Always equal to 1 (100%)
- Q = Recessive (aa)
- PQ = Aa
- Allele Frequency Equation - Allele Count/Total number of alleles
- Corrected allele frequency equation - Add 2 alleles onto the allele count and divide by new total of alleles used to construct database
- Known as balding - 95% confidence interval to correct for sampling errors

- Genotype proportion equation - Allele frequency at the 1st allele x allele frequency at the 2nd allele x 2 (2pq)
- Profile Frequency - Times the genotype frequency at each locus (product rule)

- Equation = p2 + 2pq + q2 = 1
- Deviation from the Hardy Weinberg equilibrium
- The HW law states that certain criteria must be met in order to estimate the allele and genotype frequency.
- The population is free from effects of migration
- Random mating occurs within the population
- There is no natural selection
- The population is indefinitely large
- No mutations occur
- It is clear that NO population will be able to meet all of these criteria's
- if a population does meet this criteria, then it is said to be in Hardy-Weinberg Equilibrium

- The HW law states that certain criteria must be met in order to estimate the allele and genotype frequency.
- Based on the mendelian inheritance
- Genes and traits that are passed from parent to child

- Determine frequencies of genotypes

- Once a DNA profile match has been made, the significance of the match has to be estimated.
- A population can be described as a group of people sharing common ancestry.
- it is not possible to estimate allele frequencies from the whole population as this would require testing everybody
- Population databases therefore represent a subset of the population

- it is not possible to estimate allele frequencies from the whole population as this would require testing everybody

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