Second Generation Multiplex Plus
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Second Generation Multiplex Plus (SGM Plus), is a DNA profiling system developed by Applied Biosystems. It is an updated version of Second Generation Multiplex. SGM Plus has been used by the UK National DNA Database since 1998.
An SGM Plus profile consists of a list of 10 number pairs, one number pair for each of 10 genetic markers, along with two letters (XX or XY) which show the result of the gender test. Each number pair denotes the two allele values for the marker - one value is inherited from each of the subject's parents. If both alleles are the same, then only a single number, rather than a pair, is recorded.
Genetic Markers
The genetic markers (or loci) used by SGM Plus are all Short tandem repeats (STRs). The markers used are: VWA, D8S1179, D21S11, D18S51, THO, FGA, D3S1358, D16S539, D2S1338 and D19S433. Where a marker's designation begins with D, the digits immediately following the D indicate the chromosome that contains the marker. For example, D21S11 is on chromosome 21. SGM Plus also uses the Amelogenin (Amelo) sex-indicating test.
SGM Plus differs from SGM in that SGM does not use the markers D3S1358, D16S539, D2S1338 and D19S433.
SGM Plus has eight markers in common with CODIS FGA, TH01, VWA, D3S1358, D8S1179, D16S539, D18S51, and D21S11. It differs from CODIS in that it uses the additional markers D2S1338 and D19S433 and does not use the five markers CSF1PO, TPOX, D5S818, D7S820, D13S317.[1]
| Locus Designation | Chromosome Location | Common Sequence Motif | Size Range (bp) | Dye Label |
|---|---|---|---|---|
| D3S1358 | 3p | TCTA (TCTG)1-3 (TCTA)n | 114–142 | 5-FAM |
| vWA | 12p12-pter | TCTA(TCTG)3-4(TCTA)n | 157–209 | 5-FAM |
| D16S539 | 16q24-qter | (AGAT)n | 234–274 | 5-FAM |
| D2S1338 | 2q35–37.1 | (TGCC)n(TTCC)n | 289–341 | 5-FAM |
| Amelogenin | X: p22.1–22.3 Y: p11.2 |
— | 107 113 | JOE |
| D8S117 | 8 | (TCTR)n | 128–172 | JOE |
| D21S11 | 21q11.2–q21 | (TCTA)n(TCTG)n[(TCTA)3TA(TCTA)3TCA (TCTA)2TCCA TA] (TCTA)n | 187–243 | JOE |
| D18S51 | 18q21.3 | (AGAA)n | 26–345 | JOE |
| D19S433 | 19q12–13.1 | (AAGG)(AAAG)(AAGG)(TAGG)(AAGG)n | 106–140 | NED |
| TH01 | 11p15.5 | (AATG)n | 165–204 | NED |
| FGA | 4q28 | (TTTC)3TTTT TTCT (CTTT)n CTCC (TTCC)2 | 215–353 | NED |
Dye tags
The primers are tagged with the following fluorescent dyes for detection under electrophoresis:
- 5-FAM
- JOE
- NED
The primers for each locus are arranged on the dyes in the following order, from low molecular weight to large molecular weight:
- 5-FAM: D3, VWA, D16, D2
- JOE: Amelo, D8, D21, D18
- NED: D19, THO, FGA
The dyes to which each primer is attached differ from those of the original SGM DNA profiling system.
Example SGM Plus profile
An example of an SGM Plus profile may look like this[3]:
15,18; 6,9; 11,13; 22,22; 31,32.2; 14,17; 17,20; 11,12; 13,16.3; 15,16; XY
Each value is the number of tandem repeats within the allele. A non-standard repeat is designated by the number of complete repeat units and the number of base pairs of the partial repeat, separated by a decimal point.