What causes confined placental mosaicism?
Confined placental mosaicism (CPM) This is caused by a population of cells in the placenta with three copies of the chromosome instead of the usual two. These cells are confined to the placenta and are not present in the baby. Co-twin demise When one twin was lost earlier in pregnancy due to the rare trisomy.
How common is mosaicism with CVS?
The prevalence of mosaicism in CVS for viable pregnancies at 10–12 weeks of gestation is approximately 2%. 3,7–9 When a rare autosomal trisomy (RAT, defined as any autosomal trisomy other than T21, T18, and T13) is detected in CVS, in 97% of the cases it is a CPM.
Can NIPT detect placental mosaicism?
Placental mosaicism represents the discrepancy between the genotype of the placenta and the fetus. It is an uncommon but recognised phenomenon and is known to result in false negative non-invasive prenatal testing (NIPT). The NIPT analyses the cell-free DNA derived from the placental tissue in the maternal circulation.
How often does placental mosaicism occur?
Confined placental mosaicism is rare, occurring in about 1-2% of all pregnancies.
Why is the placenta called confined placental mosaicism?
Confined Placental Mosaicism (CPM) Because the placenta and the baby come from the same cells, they have exactly the same amount of chromosomes most (98-99%) of the time. In approximately 1-2% of all pregnancies, the placenta can actually have a different chromosome makeup from the baby. This is called confined placental mosaicism (CPM).
Why are the placenta and fetus almost always the same?
Confined Placental Mosaicism is a condition characterized by the discrepancy between the chromosomal/genetic makeup of the baby and placenta. Genetic and chromosomal makeup of the placenta and fetus are almost always the same, because they both develop from the same zygote (egg)
Can a normal amniocentesis result show mosaicism?
Although a normal amniocentesis result generally suggests a normal fetal karyotype, there is still a small chance that an actual fetal mosaicism is present, meaning that some cells in the fetus are normal, such as those found in the amniotic fluid, and other cells are abnormal, such as those in other fetal tissues.
What does CPM mean in a placenta biopsy?
Chorionic villus sampling is a prenatal procedure which involves a placental biopsy. Most commonly when CPM 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.