<unk>  occurs in one of two ways: *Mitotic<unk>  - Mitotic non-disjunction can occur in a trophoblast cell or a non-fetal cell from the inner cell mass creating a trisomic cell line in the tissue which is destined to become the placental mesoderm. *Meiotic<unk>  - Alternatively,<unk>  can occur through the mechanism of trisomic rescue. If a trisomic conception undergoes trisomic rescue in certain cells, including those that are destined to become the baby, then the remaining trisomy cells may be<unk>  to the placenta. Several factors influence the pattern of normal and abnormal cells in the developing embryo. Reduced or improved replication rates of the trisomic cells could affect the number of abnormal cells compared to the number of normal cells. The abnormal cells may fail to differentiate or function properly and could be lost. It is also possible that there is no selection against the abnormal cells, but their presence could compromise the pregnancy on a whole.
Confined placental mosaicism
Germline mosaicism
Fetal programming
Robertsonian translocation
Uniparental disomy
Transplacental carcinogenesis
Postzygotic mutation
Paternal age effect