Chromosome Conditions

While prenatal testing offers more information about the pregnancy, it can also lead to many more questions such as: What do these screening results or this diagnosis mean? What kind of life does a person with this diagnosis live? Where can reliable information about this condition be found?

Sometimes people find incorrect or out-of-date information when trying to learn about different conditions. The outcomes and attitudes about many disabilities have changed greatly in recent years. This means patients need current information about genetic conditions so that they can make informed choices about the pregnancy and find any needed services or resources.

Each of the chromosome conditions that prenatal tests look for are very different. Pregnancies with Trisomy 13 and Trisomy 18 have much higher chances for miscarriage and stillbirth. Babies who have these conditions often have serious medical and neurological issues, and only about 10% live past the first year. (1) People with Down syndrome typically have mild to moderate intellectual disabilities and some medical issues that can be treated with good health care. They are usually active members of their communities and live an average of 60 years. (2) On the other hand, the effect of an extra or missing sex chromosome (such as Turner syndrome, Klinefelter syndrome, and 47,XXX) can be so mild that people might not even know they have a chromosome condition.

For current information about prenatally diagnosed conditions, patients can speak with their obstetric medical care provider or genetic counselor and search the websites of national organizations found below.

Genetic counselors and medical geneticists can be found by asking for a referral or searching online at the National Society for Genetic Counselors or the American College of Medical Genetics and Genomics.

Prenatal screening and testing are constantly changing to include more conditions. Therefore, it is important for patients to talk to their medical providers about what conditions are included in the different testing options.

  1. Rasmussen et al. Population-based analyses of mortality in trisomy 13 and trisomy 18. Pediatrics. 2003 Apr;111(4 Pt 1):777-84.
  2. Glasson, E.J., Sullivan, S.G., Petterson, B.A., Montogomery, P.D., & Bittles, A.H. (2002). The changing survival profile of people with Down syndrome: implications for genetic counselling. Clinical Genetics, 62: 390-393.


For more information about prenatal testing and prenatally diagnosed conditions, click below:

Screening Tests
Diagnostic Testing
Understanding Chromosome Conditions
Trisomy Conditions (Down syndrome, Trisomy 18, and Trisomy 13)
Sex Chromosome Conditions (Turner syndrome, Klinefelter syndrome)
Neural Tube Defects (Spina Bifida)
Microdeletions (Angelman/Prader-Willi, 22q, Wolf-Hirschhorn, Cri-du-Chat, Jacobsen, and Williams syndrome)

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