noun
definition
The presence of three copies, instead of the normal two, of a particular chromosome of an organism.
Examples of trisomy in a Sentence
Parental chromosome analysis should be offered where trisomy 13 is due to an unbalanced translocation.
Examples of such accidents are development of an extra chromosome 18 (trisomy 18) and Down syndrome.
Patau syndrome, also called trisomy 13, is a congenital (present at birth) disorder associated with the presence of an extra copy of chromosome 13.
Patau syndrome is named for Klaus Patau, who reported the syndrome and its association with trisomy in 1960.
A condition called trisomy occurs when three, instead of two, copies of a chromosome are present in a developing human embryo.
The most well-known trisomy-related disorder is Down syndrome (trisomy 21), in which the developing embryo has an extra copy of chromosome 21.
Patau syndrome is trisomy 13, in which the developing embryo has three copies of chromosome 13.
Full trisomy 13, which is present in the majority of the cases, results in the most severe and numerous internal and external abnormalities.
Frequently, a child with trisomy 13 has a cleft lip, a cleft palate, or both.
Partial trisomy of the proximal segment of chromosome 13 is much less likely to be fatal and has been associated with a variety of facial features including a large nose, a short upper lip, and a receding jaw.
Trisomy 13 is confirmed by examining the infant's chromosomal pattern through karyotyping or another procedure.
Approximately 45 percent of trisomy 13 babies die within their first month of life; up to 70 percent in the first six months; and over 70 percent by one year of age.
Edwards' syndrome is also referred to as trisomy 18, trisomy E, and trisomy 16-18.
It is the second most common trisomy, after trisomy 21 (Down syndrome).
Down syndrome is a condition that includes mental retardation and a distinctive physical appearance linked to an abnormality of chromosome 21 (called trisomy 21).
It also is associated with Down syndrome (trisomy 21).
Some brain defects are caused by trisomy, the inclusion of a third copy of a chromosome normally occurring in pairs.
Trisomy of chromosome 9 can cause some cases of Dandy-Walker and Chiari II malformation.
Some cases of holoprosencephaly are caused by trisomy of chromosome 13, while others are due to abnormalities in chromosomes 7 or 18.
Called nuchal translucency, the measurement tends to be larger in fetuses with genetic abnormalities such as Down syndrome, trisomy 13, trisomy 18, Turner syndrome, and triploidy.
For this reason, the existence of three such chromosomes is sometimes referred to as trisomy 21.
The blood test given during the first trimester screening is for chromosomal abnormalities in the baby, including Down's Syndrome (trisomy 21), Edwards Syndrome (trisomy 18), skeletal defects, or heart defects.
Alterations in chromosomes causing Down syndrome and Trisomy 18 birth defects are considered structural genetic birth defects.
Where trisomy 18 is caused by an unbalanced chromosomal translocation, chromosomal analysis should be carried out on both parents.