Can you explain about mosaicism detected by prenatal diagnosis?
When a prenatal test, like amniocentesis, is done, the cells that are collected have to be grown up. You want to set up several lines to make sure you get clear results. When you have enough cells, multiple metaphases are counted and analyzed, then several are karyotyped. The problem arises when some cells show mosaicism. Mosaicism is the post-fertilization occurrence of two or more cell lines with different genetic or chromosomal constitutions within a single individual or tissue. When you find it in a culture of fetal cells, it needs to be determined if the fetus is a mosaic or if the finding is clinically significant. Cytogenetists have divided it into 3 categories, pseudomosaicism, true mosaicism and maternal contamination. A single or several weird cells from a single primary culture are usually classed as pseudomosaicism. True mosaicism is detected in multiple colonies from several different primary culture lines, and is associated with a high probability that the fetus is a mosa
