Allele-specific detection of single mRNA molecules in situ.

We describe a method for fluorescence in situ identification of individual mRNA molecules, allowing quantitative and accurate measurement, in single cells, of allele-specific transcripts that differ by only a few nucleotides. By using a combination of allele-specific and non-allele-specific probe libraries, we achieve >95% detection accuracy. We investigate the allele-specific stochastic expression of Nanog, which encodes a pluripotency factor, in murine embryonic stem cells.