Digital PCR for discriminating mosaic deletions and for determining proportion of tumor cells in specimen

Mosaicism, presence of a genetic feature in only a subpopulation of cells, is frequent in de novo genetic diseases. Among large deletions covering the NF1 tumor suppressor gene, the frequency of mosaicism can be as high as 40% in de novo patients. In this study, we demonstrate the high potential of digital PCR in detecting large NF1 deletions and in discriminating mosaic cases. By simultaneously assessing the NF1 gene and a reference gene RPP30, deletions could be unambiguously distinguished from non-deletion samples. Performing the same assay for mixed samples from a DNA with a deletion and a non-deletion DNA, a highly significant linear relation was obtained between the set-up ratio of the two samples and the measured ratio of NF1/RPP30 (P