Genotype assessment of a single SNP by pyrosequencing using two different primer oligonucleotides and heterozygous test samples. Below each pyrogram series, the respective sequencing primer (indicated by arrow) and incorporated bases (bold letters) are shown. Primers were extended in the sense direction. The ordinate represents luminescence (arbitrary units). Arrowhead doublets indicate the location of SNPs. The polymorphic position, addressed in both panels, corresponds to position A1166C in exon 5 of human angiotensin II type I receptor gene. (Upper panel) Extension of a sequencing primer, juxtaposed to the biallelic position. (Lower panel) Synthesis from a primer, located four bases upstream of the SNP.