This information provided through these links is not comprehensive. Specific questions should be addressed to your doctor.
Links to information about specific abnormalities in the number of chromosomes
Conditions that can be identified by standard NIPT:
Conditions that can be identified by screening for sex chromosome abnormalities:
Abnormalities in the number of X and Y chromosomes typically cause fewer problems than the common trisomies of chromosomes 21, 18 and 13. This is not surprising as healthy men and women have different numbers of these chromosomes: males have an X and a Y chromosome (XY), while females have two X chromosomes (XX). If a male has an extra Y chromosome (XYY) or a female has an extra X chromosome (XXX), there is usually nothing in their appearance, development or fertility to suggest that they have a third sex chromosome. On the other hand, absence of an X chromosome (monosomy X) and an additional X chromosome in a male (XXY) cause impaired fertility, are associated with leaning difficulties, and may cause abnormalities of the heart or kidneys.
Conditions that can be identified by genome-wide NIPT
Genome-wide NIPT is designed to look for certain abnormalities across most chromosomes i.e. for gains or loss of a chromosome segment in any chromosome (excluding X and Y chromosomes) and for a mix of normal cells and cells with an abnormal number of any chromosome (excluding X and Y in twins). The significance of these abnormalities depends both on the chromosome abnormality itself and the results of other investigations arranged by your doctor.
In general terms,
- the gain or loss of a large chromosome segment is usually associated with a high chance of a fetal abnormality. You doctor may recommend that you and your partner be tested to see if either of you has the same gain or loss; if a healthy parent has the same gain or loss, it is unlikely to cause a medical problem in the fetus. Most of the gains or losses are new events that occurred at conception, and neither parent has the abnormality.
- The presence of a mixture of normal and abnormal cells (i.e. with an abnormal number of chromosomes) is often due to the abnormal cells being limited to the placenta and the fetus having normal chromosomes. In this situation, the fetus may develop normally. On the other hand, the chromosome abnormality in the placenta may cause it to function poorly, limiting the growth and development of the fetus. It is also possible that the mixture of normal and abnormal cells does involve the fetus. These various possibilities would be examined by your doctor or a specialist obstetrician.
We cannot provide specific information about the many different conditions involving the fetus or placenta that may be identified by such a test. Please ask your doctor to discuss the range of possible outcomes with you.
The information on this website is provided for your general information and is not a substitute for the specific advice of your treating doctor.