Down Syndrome is the most common chromosome abnormality and one of the most well-known genetic disorders. It causes the most frequent form of intellectual disability developed by a mutation. According to the Centers for Disease Control and Prevention (CDC), 1 in 700 babies will have the disease. Some of the most known physical features of the syndrome are up slanting palpebral fissures, epicanthic folds, brachycephaly, open mouth, and flat facial profile.
October is Down Syndrome awareness month. In order to spread awareness, it could be great to learn together about the root of the disorder. It starts from the moment a mother identifies that she might be at risk of having a child with Down Syndrome. (Per HIPAA regulations, all the patient information below is fictional, and it is not intended to portray any real person’s medical information.)
So, today I present to you the case of Mrs. Doe.
Name: Mrs. Doe
Age: 43 y/o
Reason for coming to the doctor: Mrs. Doe is 2 months pregnant. She mentions having interest in getting her baby tested for Down Syndrome as part of her prenatal care. She expresses concern because of her age and lack of knowledge about the tests.
Causes: The physician explains to Mrs. Doe that this syndrome is caused by genetic abnormalities such as the following:
- Trisomy 21 (~95%): It is caused by trisomy 21. The patient has three copies (instead of two) of chromosome 21 in all their cells. This is caused by problems with cell division during development.
- Translocation Down syndrome: A portion of chromosome 21 becomes translocated onto another chromosome. The patient has two copies of chromosome 21 and additional genetic material from chromosome 21 attached to another chromosome or translocated to another chromosome.
- Mosaic Down syndrome: In this rare form of the syndrome not all the cells have the trisomy 21, causing a mosaic of normal and abnormal cells.
- A woman’s risk of giving birth to a child with Down syndrome is greater after 35 years of age.
- Parents being carriers of the genetic translocation responsible for Down syndrome.
- Parents of a child with Down syndrome are at an increased risk of having another child with the syndrome.
Genetic counseling: Referral to a genetic counselor or a medical geneticist in order to address Mrs. Doe’s concerns.
Some of the topics discussed in genetic counseling include the following:
- The risks of diagnostic tests
- Information about continuing the pregnancy after diagnosis (i.e. pediatric care, resources for families with an affected child)
- Information about the option of pregnancy termination
- Help parents assess the risk of having another child with Down syndrome
Screening and Diagnostic tests:
Table I. Screening tests
Table II. diagnostic tests
Once Mrs. Doe and her husband have decided what tests they are interested in and that the results are available. Their healthcare providers will follow the National Society of Genetic Counselor recommendations and or guidelines for communicating a prenatal or postnatal diagnosis of Down syndrome to parents. Some of the recommendations include the following:
- Inform the parents about the results as soon as possible.
- Provide referrals to specialists when appropriate (i.e. medical geneticist, cardiologists, etc.)
- Discuss possible pregnancy outcomes (i.e. miscarriage, surgical issues, etc.)
- Avoid using terms such as: “I’m sorry” or “Unfortunately, I have bad news,” when starting the conversation.
- Among other recommendations
Down syndrome. (2018, March 08). Retrieved September 29, 2020, from https://www.mayoclinic.org/diseases-conditions/down-syndrome/symptoms-causes/syc-20355977
Facts about Down Syndrome. (2019, December 05). Retrieved September 29, 2020, from https://www.cdc.gov/ncbddd/birthdefects/downsyndrome.html
Messerlian, G. M., Palomaki E.G (2020). Down syndrome: Overview of prenatal screening. Retrieved October 01, 2020, from https://www-uptodate-com.aucmed.idm.oclc.org/contents/down-syndrome-overview-of-prenatal-screening?search=Down+syndrome%2C+pregnancy
Pagano, T. (2020, September 09). Chorionic Villus Sampling: Purpose, Procedure, Risks, Results. Retrieved October 01, 2020, from https://www.webmd.com/baby/chorionic-villus-sampling
Brennan, D. (2019, May 05). Testing for Down Syndrome During Pregnancy. Retrieved October 02, 2020, from https://www.webmd.com/children/test-check-down-syndrome-pregnancy
Sheets, K., Crissman, B., Feist, C., Sell, S., Johnson, L., Donahue, K., . . . Brasington, C. (2011, May 27). Practice Guidelines for Communicating a Prenatal or Postnatal Diagnosis of Down Syndrome: Recommendations of the National Society of Genetic Counselors. Retrieved October 02, 2020, from https://onlinelibrary.wiley.com/doi/10.1007/s10897-011-9375-8