Rapid chromosome identification by oligonucleotide-primed in situ DNA synthesis (PRINS)

We describe a method for rapid identification of chromosomes at metaphase, and quantification of chromosomes in interphase, by annealing oligonucleotide primers, derived from chromosome-specific subsets of repeated DNA families, to the DNA of cytological preparations, and enzymatic extension with the incorporation of labelled nucleotides. The method is equally applicable to normal cells or those from somatic cell hybrids. Where the labelled product is too small or of too low a copy number to be readily seen after the single extension reaction, we have developed a method for cyclic amplification of the labelled DNA, enabling clear visualization of the signal.