<unk>  <unk>  represents a discrepancy between the chromosomal makeup of the cells in the placenta and the cells in the fetus.<unk>  was first described by Kalousek and Dill in 1983.<unk>  is diagnosed when some trisomic cells are detected on chorionic villus sampling and only normal cells are found on a subsequent prenatal test, such as amniocentesis or fetal blood sampling. In theory,<unk>  is when the trisomic cells are found only in the placenta.<unk>  is detected in approximately 1-2% of ongoing pregnancies that are studied by chorionic villus sampling (CVS) at 10 to 12 weeks of pregnancy. Chorionic villus sampling is a prenatal procedure which involves a placental biopsy. Most commonly when<unk>  is found it represents a trisomic cell line in the placenta and a normal diploid chromosome complement in the baby. However, the fetus is involved in about 10% of cases.
Confined placental mosaicism
Germline mosaicism
Fetal programming
Robertsonian translocation
Uniparental disomy
Transplacental carcinogenesis
Postzygotic mutation
Paternal age effect