Additional STR allele frequency information can be added to improve the analysis in Problem 8. The frequency of D8S1179₁₂ = 0.12. The frequency of D16S539₁₈ = 0.08 and of D16S539₂₀ = 0.21. Lastly, D18S51₁₉ = 0.13 and D18S51₂₀ = 0.10. Combine the allele frequency information for these three STR genes with the information used in Problem 8 to calculate the frequency of the genotype for six of the STR genes.

Key Concepts

Short Tandem Repeats (STRs)

Short Tandem Repeats (STRs) are repeating sequences of 2-6 base pairs of DNA that are found in various locations in the genome. They are highly polymorphic, meaning that the number of repeats can vary among individuals, making them useful for genetic profiling and forensic analysis. STRs are commonly used in DNA fingerprinting because their variability allows for the differentiation of individuals based on their unique genetic makeup.

Allele Frequency

Allele frequency refers to how often a particular allele appears in a population compared to other alleles for the same gene. It is expressed as a proportion or percentage and is crucial for understanding genetic diversity and population structure. In the context of STR analysis, knowing the allele frequencies helps in calculating the probability of a specific genotype occurring within a population, which is essential for applications like paternity testing and forensic investigations.

Genotype Frequency Calculation

Genotype frequency calculation involves determining the likelihood of a specific combination of alleles occurring in a population. This is done by multiplying the frequencies of the individual alleles that make up the genotype. For STR analysis, combining the allele frequencies of multiple loci allows researchers to estimate the overall frequency of a particular genotype, which is vital for assessing the rarity or commonality of that genotype in the context of forensic or population studies.