Identification of marker chromosomes by reverse painting fluorescence in situ hybridization and comparative genomic hybridization / 대한산부인과학회지

ABSTRACT

OBJECTIVE: Although marker chromosome is defined as an abnormal chromosome in which no part can be identified, derivative chromosomes with structural abnormalities of unknown origin are also called as marker chromosomes conventionally. The clinical significance of a marker chromosome is determined according to the origin of marker chromosome. In this study reverse painting fluorescence in situ hybridization (FISH), and comparative genomic hybridization (CGH) methods were employed to elucidate the origin of marker chromosomes in 5 clinical cases. METHODS: Reverse painting probes were generated from five copies of each marker chromosomes microdissected with micromanipulator, amplified with DOP-PCR, and labeled with fluorochromes. The probes were hybridized to normal metaphases. For CGH, normal control and patients' DNA were directly labeled with spectrum-red-dUTP and spectrum-green-dUTP by CGH nick translation kit, and hybridized to normal reference metaphases. The CGH images were captured with a computer controlled fluorescence microscope equipped with a CCD camera and analyzed by Cytovision workstation. RESULTS: Five marker chromosomes were identified as follows (1) derivative chromosome 15 inducing partial trisomy of 15pter->q21, (2) isochromosome of 18p causing 18p tetrasomy, (3) short arm of chromosome 5 causing 5p trisomy (4) small accessory chromosome originated from centromeric region of chromosome Xq11->q12 (5) der(17) with inverted duplication of the short arm of chromosome 17. In all cases the origin of each marker chromosomes were identified successfully with reverse painting FISH, and these results were concordant with the CGH profiles. CONCLUSION: Our results indicate that combined reverse painting FISH and CGH is a rapid, convinient and powerful tool to identify the origin of marker chromosomes and derivative chromosomes caused by various chromosome abnormalities such as translocation, duplication, deletion.