How is Edwards Syndrome Caused?

Edwards Syndrome

Edwards syndrome, also known as trisomy 18, is a chromosomal disorder caused by the presence of an extra copy of chromosome 18. This additional genetic material disrupts normal development and leads to various abnormalities and health problems. Edwards syndrome is a type of trisomy, where there are three copies of a particular chromosome instead of the usual two.

The most common cause of Edwards syndrome is a random error in cell division during the formation of either the egg or the sperm. This error is known as nondisjunction, and it results in an abnormal number of chromosomes in the affected individual. In the case of Edwards syndrome, the error usually occurs in the egg cell.

There are two main types of trisomy 18:

  • Full Trisomy 18: This is the most common form, where each cell in the body has three copies of chromosome 18. Full trisomy 18 typically results from nondisjunction during the formation of the egg cell.
  • Mosaic Trisomy 18: In this form, some cells have the usual two copies of chromosome 18, while others have three copies. Mosaic trisomy 18 may result from errors in cell division after fertilization.

It’s important to note that Edwards syndrome is not caused by anything the parents did or did not do during pregnancy. The occurrence of trisomies is generally considered a random event. The risk of having a child with Edwards syndrome increases with maternal age, particularly in women over the age of 35, but it can occur in pregnancies at any maternal age.

Edwards syndrome is associated with a range of physical and intellectual disabilities, as well as congenital abnormalities affecting various organs. Many affected individuals have a significantly shortened lifespan, with a majority of pregnancies ending in miscarriage or stillbirth. Those who survive beyond birth often face severe health challenges and may require ongoing medical care.

Prenatal testing, such as chorionic villus sampling (CVS) or amniocentesis, can be used to diagnose Edwards syndrome during pregnancy by examining the fetal chromosomes. Genetic counseling is often recommended for parents who may be at increased risk or who have received a diagnosis of Edwards syndrome during pregnancy.

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