Schematic illustration of RQPS. A RQPS probe, which consists of a DNA fragment from the query gene physically linked to a DNA fragment from a reference gene, both containing artificially designed SNVs, is mixed with genomic DNA samples to attain a molar ratio between 1:9 and 9:1. The molar ratio of R-SNV, Q-SNV between probe and sample genomic DNA in each mixture is accurately determined by quantitative pyrosequencing. If the query gene is diploid, %G/%A = T%/C% (wild type, WT in the diagram). If one copy of the query gene is lost, %G/%A < T%/C% (loss of homozygosity, LOH in the diagram). If multiple copies of the query gene are present, then %G/%A > T%/C%. See text for details.
