Karyotype analysis in the diagnosis of 1. chromosome chimera
Karyotype analysis as a chimera cannot be used as the gold standard, because not all cells grow and divide in the process of cell culture, and only amniotic cells can do chromosome examination, which is incomplete. Even amniotic cells can't grow completely, and some abnormal cells are not suitable for in vitro culture environment and are easy to die; There are also some cells that become abnormal during culture; Therefore, the final test results are not completely representative.
2. Diagnosis of chromosome chimera by gene chip technology.
Gene chip and gene sequencing, molecular biology technology, can not be used as the gold standard of chimera detection, because they mix all cells together to detect, obliterating individuality. If half the cells are haploid and the other half are trisomy; It may not be detected by chip and CNV sequence, and the result is normal. The calculated average, but the actual cell chromosomes are very different, which is easy to be inaccurate.
3. Diagnosis of chromosome chimera by FISH technology.
FISH belongs to molecular cytogenetics technology, which can make up for the shortcomings of the above two methods and can accurately and reliably detect chimeras and proportions.
When doing FISH examination, the cells taken out of amniotic fluid are first laid flat on a glass sheet, and then probes at specific chromosome positions (each chromosome has a specific probe) are labeled with fluorescence and added to this glass sheet. These probes will enter cells and bind to specific chromosomes. After the probe is completely and stably combined with the cell, the redundant probe is washed away. Then put the slide under a fluorescent microscope. Because the probe is inside the cell, it will emit fluorescence. A probe and a fluorescent signal point can be counted cell by cell. How many fluorescent signals each cell has means that there are several corresponding chromosomes.
Compared with chromosome karyotype and molecular genetics technology, fish do not need to be cultured, and there will be no breeding deviation; Fish is a single cell observation, and there will be no problem of mixing together to obliterate personality. Therefore, FISH is particularly suitable and reliable for chimera detection.