In-cell polymerase chain reaction: strategy and diagnostic applications.

In situ polymerase chain reaction (PCR) refers to the amplification of specific nucleic acid sequences and subsequent visualization of the PCR products in tissue sections. When PCR is performed in fixed cells in suspension the term in-cell PCR is normally applied instead. For example, in-cell PCR has been used for intracellular detection of specific viruses. Furthermore, in mixtures of cells in suspension with different genotypes, in-cell PCR may be used for intracellular detection of DNA or mRNA sequences specific for one of the genotypes/population of cells. An in-cell PCR method is described that makes it possible to genotype a specific gene of interest derived from one individual in a mixture of cells from two individuals. This new method is based on in-cell PCR and dependent upon the presence of a well characterized and specific DNA sequence or polymorphism, which has to be present only in the cells from the individual being genotyped for the gene sequence of interest. The in-cell PCR method might find diagnostic applications in detection of intracellular pathogenic sequences in subgroups of cells and in noninvasive prenatal genetic diagnoses with the use of the few fetal cells circulating in maternal blood.