Triploidy is a chromosomal abnormality with the constitution 69,XXY , or, less commonly, 69,XXX. It occurs in 2% of all conceptions with resulting early spontaneous abortion.
In most cases, the extra set of chromosomes is paternally-derived, either from double fertilisation, or from fertilisation with a double sperm.
Clinically, if the triploid fetus survives to term, the following may present:-
- low birth weight
- disproportionately small trunk to head size
- multiple congenital abnormalities
- large placenta with hydatidiform-like changes
The recurrence risk does not seem to be increased in affected parents.
Last reviewed 01/2018