Short tandem repeat (STR) profiling in forensic DNA analysis is MOST useful because:
- A STRs are highly polymorphic non-coding repetitive sequences; the number of repeats at multiple loci gives a highly individual-specific profile ✓
- B STR sequences are protein-coding exon regions and thus species-specific
- C STR analysis can be performed on RNA from hair follicles without DNA extraction
- D STR loci are mitochondrial and thus maternally inherited, enabling maternal lineage identification
Explanation
Short tandem repeats (STRs, microsatellites) are 2–7 base pair repetitive non-coding sequences dispersed throughout the genome that show high polymorphism in the number of repeat units between individuals. Typing multiple STR loci (typically 13–21 in CODIS and similar systems) produces an extremely discriminating genetic profile with a match probability of less than 1 in a quadrillion unrelated individuals. STR analysis is performed on nuclear DNA (not mitochondrial); mitochondrial DNA (inherited maternally) is used separately for degraded samples. STRs are not protein-coding and are useful precisely because their high polymorphism makes individual identification highly reliable.
Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.
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Written and medically reviewed by the StethoPrep medical team.