Schematic of SNPSTR system depicting double heterozygote autosomal genohaplotype for a diploid organism. In this example, one homolog has a C allele at the SNP and an STR of 21 repeat units. The other homolog has a T allele at the SNP and an STR of 23 repeat units. The C allele is amplified via PCR with an allele-specific primer, with C at the 3′ terminus, and is labeled with the fluorescent dye 6-FAM. The T allele is amplified with an allele-specific primer, with T at the 3′ terminus, and is labeled with the fluorescent dye HEX. Both labeled PCR products are produced with the same reverse primer “r.” As the length of the PCR product varies depending solely upon the repeat number of the STR, and length is determined by fluorescent detection of electrophoretic mobility, the allelic states of the SNP and STR, and gametic phase, are all determined simultaneously by fluorescent electrophoretic fragment analysis.
