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DNA Amplification for Forensic Analysts

Locus Size and Overlap

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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 are available.  These data provide 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.

DNA Amplification - Locus Size
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