- Course Introduction
- 01: Evidence & DNA
- 02: Forensic Biology
- 03: DNA Extraction & Quantitation
- 04: DNA Amplification
- Overview
- Introduction
- Amplification
- Primer Design
- Primer Length
- Primer Melting Temperature
- Primer Annealing Temperature
- Values for Tm
- Maximum 3′ Stability
- GC Content Percentage
- No Secondary Structures
- No Self-complementarity
- No Complementarity To Other Primers
- No Long Runs With The Same Base
- Distance Between Two Primers On Target Sequence
- Plateau Effect
- Thermal Cyclers
- Thermal Cycling Parameter and Optimization
- Works Cited & Online Links
- Locus Selection
- Multiplexing
- Contamination
- Overview
- 05: Amplified DNA Product Separation
- 06: STR Data Analysis & Interpretation
- 07: Population Genetics & Statistics
- 08: Communicating Results
- 09: Other DNA Markers & Technologies
- Course Resources
- Laboratory Training Manual
President's DNA Initiative
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Advancing Justice Through DNA Technology
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Advancing Justice Through DNA Technology
DNA Analyst Training
Locus Size and Overlap
Home > DNA Amplification > Multiplexing > Factors > Locus Size and Overlap
The STR loci of interest fall into a size range of 75-400 base pairs. Designing the multiplex requires consideration of the competing demands of locus size. A narrow size range minimizes allelic dropout and permits balanced amplification; a broader size range minimizes overlap between the loci, permitting more reliable allele calls.
Many STR loci have been well characterized and population data is available. This data provides information on the allele size range of the locus. Multiplexes are designed to minimize overlap so that the smallest allele for one locus is larger than the largest allele of the adjacent locus within the same dye.
