Trisomy is the answer.
A trisomy is a chromosome abnormality in which a person has three copies of a particular chromosome rather than the expected two.
Trisomies can have varying effects on a person's health depending on which chromosome is affected by the trisomy. Some trisomies such as trisomy x have only mild effects whereas others such as trisomy 21 also known as Down syndrome result in health problems and development delays.
Many Trisomies can have fatal consequences such as trisomy 16 or trisomy 18 .They frequently cause miscarriages or loss of the baby shortly after birth.
