<unk>  is a chromosomal abnormality in which there are three copies of chromosome<unk>  rather than two. It is the most common chromosomal cause of miscarriage during the first trimester of pregnancy.
It is not possible for a child to be born with an extra copy of this chromosome present in all cells (called Full<unk> .
It is possible to be born with the mosaic form.
Trisomy 16
Trisomy 22
Trisomy 9
Spina bifida
Anencephaly
Partial monosomy 13q
XX gonadal dysgenesis
Caudal regression syndrome