Forensic scientists rely heavily on commercially available kits to perform DNA testing (see Chapter 5). Thus, many laboratories especially in the U.S. have been reluctant to move into Y-STR typing until Y-STR kits were offered. The first kit was Y-PLEX™ 6 from ReliaGene Technologies (New Orleans, LA), which co-amplifies DYS19, DYS389II, DYS390, DYS391, DYS393, and DYS385 a/b (Figure 9.6). Table 9.3 lists the kits that were available as of June 2004 and the loci that they amplify. Kits that enable a single amplification of all the minimal haplotype and SWGDAM recommended loci are now available.
ReliaGene Technologies sells the Y-PLEX™ 12 kit, which amplifies the SWGDAM recommended loci plus the amelogenin marker (see Chapter 5). Inclusion of amelogenin enables confirmation that the PCR reaction has not failed on female DNA samples since a single X amplicon will result. In addition, mixture levels of male and female DNA can be confirmed with the amelogenin X and Y peak height ratios (see Chapter 7). While the amelogenin primers provide a measure of quality control on PCR amplifications, they have the disadvantage of possibly tying up and consuming PCR reagents when high levels of female DNA are present in a mixture. Shewale et al. (2003b) found that male-female mixtures down to 1:400 still resulted in the male component amplifying at the Y-STR loci.
125 150 175 200 225 250 275 300 325 350 375 400
8000 7000 6000 5000 4000. 3000. 2000. 1000. 0
Figure 9.6 Result from the commercial Y-STR kit Y-PLEX™ 6.
Kit Name (Source)
Dye Color Loci Amplified Arranged by Size
(ReliaGene Technologies) Y-PLEX™ 5
genRES® DYSplex-1 (Serac, GERMANY)
genRES® DYSplex-2 (Serac, GERMANY)
PowerPlex® Y (Promega Corporation)
MenPlex® Argus Y-MH (Biotype, GERMANY)
January 2001 July 2002
January 2004 Fall 2004
DYS393, DYS19, DYS389II DYS390, DYS391, DYS385a/b
DYS389I, DYS389II DYS439
DYS390, DYS39I, DYS385 a/b Amelogenin, DYS5389 I/II
DYS392, DYS393 DYS19, DYS389 I/II
DYS392, DYS390, DYS385 a/b DYS393, DYS389I, DYS391, DYS389II Amelogenin, DYS19, DYS439, DYS438
DYS391, DYS389I, DYS439, DYS389II DYS438, DYS437, DYS19, DYS392 DYS393, DYS390, DYS385 a/b
DYS393, DYS390, DYS385 a/b
DYS391, DYS19, DYS389I, DYS392, DYS389II
DYS456, DYS389I, DYS390, DYS389II DYS458, DYS19, DYS385a/b DYS393, DYS391, DYS439, C4, DYS392 H4, DYS437, DYS438, DYS448
Commercially available Y-STR hits. Characteristics of each locus may be found in Table 9.2. An internal size standard is typically run in the fourth or fifth dye position on multi-color fluorescence detection systems for allele sizing purposes. Dye colors = Blue (B), Green (G), Yellow (Y), or Red (R). The underlined loci, such as DYS437present in the PowerPlex Y hit, are not part of the minimal haplotype or SWGDAM recommended loci.
A major advantage in having commercial Y-STR kits is the availability of common allelic ladders. These allelic ladders provide a consistent currency that aids in quality assurance of results as well as compatibility of results going into DNA databases. The allelic ladders for the DYS385 locus with the Y-PLEX 12 and PowerPlex Y kits are shown in Figure 9.7. As was noted in Chapter 5 with autosomal STR markers, various kits differ with the alleles present in their ladders. Hence the ability to reliably call a DYS385 allele 23 is greater with the PowerPlex Y ladder since this rare allele is present in PowerPlex Y but outside the range of the Y-PLEX 12 ladder rungs.
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