What genetic markers are commonly used in forensic DNA fingerprinting and how are they analyzed?

What genetic markers are commonly used in forensic DNA fingerprinting and how are they analyzed?

• A. Mitochondrial DNA sequencing alone provides unique identification.
• B. STRs are analyzed by hybridization patterns on arrays.
• C. Short tandem repeats are amplified by PCR and analyzed by sizing; unique combination identifies individuals.
• D. SNP allele frequency alone uniquely identifies individuals.

Answer: (C)

Short tandem repeats drive forensic DNA fingerprinting because they are highly variable in the population. In practice, labs amplify these STR regions with PCR and then determine their lengths by sizing the PCR products. Each locus has a repeat count that translates to an allele size, and a person’s DNA profile is the combination of allele sizes across many STR loci. The chance that two unrelated people share the same pattern across all those loci is extremely low, making the profile highly distinctive (identical twins aside). Mitochondrial DNA analysis isn’t typically used alone for individual identification because mtDNA is inherited from the mother and has less overall variation, so it’s great for tracing maternal lineage or analyzing degraded samples but not for unique identification in most cases. An array-based hybridization approach isn’t the standard method for STR typing, which relies on PCR and sizing rather than hybridization patterns. And a single SNP allele frequency doesn’t uniquely identify an person either; many SNPs must be considered together, and STR panels have historically provided the strongest discriminatory power in forensic identification.

Short tandem repeats drive forensic DNA fingerprinting because they are highly variable in the population. In practice, labs amplify these STR regions with PCR and then determine their lengths by sizing the PCR products. Each locus has a repeat count that translates to an allele size, and a person’s DNA profile is the combination of allele sizes across many STR loci. The chance that two unrelated people share the same pattern across all those loci is extremely low, making the profile highly distinctive (identical twins aside).

Mitochondrial DNA analysis isn’t typically used alone for individual identification because mtDNA is inherited from the mother and has less overall variation, so it’s great for tracing maternal lineage or analyzing degraded samples but not for unique identification in most cases. An array-based hybridization approach isn’t the standard method for STR typing, which relies on PCR and sizing rather than hybridization patterns. And a single SNP allele frequency doesn’t uniquely identify an person either; many SNPs must be considered together, and STR panels have historically provided the strongest discriminatory power in forensic identification.