Primed in situ (PRINS) labeling for rapid detection of numeric and structural chromosome anomalies

Primed in situ (PRINS) labeling has been applied to replace the traditional fluorescence in situ hybridization (FISH) method for the detection of specific sequences in situ in several numerical and structural chromosome anomalies. PRINS is based on sequence-specific annealing in situ of an unlabeled DNA probe or oligonucleotide primer. The probe serves as a primer for chain elongation in situ, using the labeled nucleotides as substrate. An oligonucleotide, (CCCTAA) representing human telomeric sequences, was mixed with nucleotides, biotin-16-dUTP, and Taq DNA polymerase, and applied on metaphase slides with ring chromosomes 4, 13, 18, X and Y. Primers for alpha-satellite sequences specific for the centromeric regions of human chromosomes 13, 15, 18, X and Y were also used to characterize the nature and origin of unidentifiable supernumerary marker chromosomes. The specificity of PRINS in differentiating centromeric sequences of chromosome [3 from 21 which is not possible with FISH, was demonstrated. Absence of the telomeric sequences in all of the ring chromosomes was noted in normal and abnormal phenotypes. The results suggest a mechanism of ring formation, an end-to-end fusion after loss of the palindromic nucleotide sequences at the telomeres PRINS, a fast and sensitive method of detecting nucleic acid sequences in situ, may be a reliable technique for detecting chromosomal aneuploidies and some structural rearrangements.