DNA sequencing of RT-PCR products can be used to detect monoallelic expression.

Chromatograms show the DNA base sequence as ordered peaks of differently-colored lines. Green line peaks represent adenine (A); black line peaks represent guanine (G). These chromatograms show results for the pink-eye gene sequence in mouse neural stem cells. Top panel: Controls show a G versus A difference (SNP) between the two parental strains (Q and R) in the pink-eye gene. Mice from the two strains are crossed to produce Q x R hybrid mice. The chromatogram at the right shows that, in cell mixtures from these hybrid mice, both alleles are expressed (A & G). Bottom panel: Clonal cell lines are derived from Q x R hybrid mice. These clonal cell lines express RNA from only one allele or the other. Clone 1 (left) expresses the sequence with A. Clone 2 (right) expresses the sequence with G. (Results are modified from Wang et al., PLoS ONE, 2007).