What is Trisomy 18?

What causes it?

At conception, 23 chromosomes from the father and 23 chromosomes from the mother combine to create a baby with 46 chromosomes in each cell, two of each type. Each chromosome holds a particular "position" in the cell and carries certain genetic material. A trisomy occurs when a baby has three chromosomes in one position instead of the normal two. The most common trisomy is Trisomy 21, also known as Down Syndrome, where a baby has three of the twenty-first chromosome. Trisomy 18 is the second most common trisomy and occurs when a baby has three of the eighteenth chromosome. This results in 47 chromosomes instead of the normal 46 in the affected cells. It is this extra genetic material that causes the problems associated with Trisomy 18.

Trisomy 18 is also called Edwards syndrome (or Edward's syndrome) and occurs in about 1:3000 live births. Unlike Down syndrome, Trisomy 18 is usually fatal, with most of the babies dying before birth and those who do make it to birth typically living only a few days. However, a small number of babies (<10%) live at least one year. Most trisomies (about 95%) are full trisomies. That is, the extra chromosome occurs in every cell in the baby's body. This type of trisomy is not hereditary, and is not due to anything the parents did or did not do, and it is by far the most common type. In most literature, Trisomy 18 means full Trisomy 18. 

What are the characteristics of Trisomy 18?

The extra genetic material from the additional eighteenth chromosome can cause a variety of problems with varying severity. Just as children with Down Syndrome can range from mildly to severely affected, so can children with Trisomy 18. Therefore there is no hard and fast rule about what Trisomy 18 will mean for your child. However statistics show that there is a high mortality rate for children with Trisomy 18 before or shortly after birth.

Some of the typical characteristics of Trisomy 18 can include heart defects such as VSD (Ventricular Septal Defect - a hole between the lower chambers of the heart) , ASD (Atrial Septal Defect - a hole between the upper chambers of the heart), and coarctation of the aorta (a narrowing of the exit vessel from the heart), kidney abnormalities, omphalocele (a portion of the intestinal tract is located outside the stomach in a sac), esophageal atresia (the esophagus does not connect to the stomach, meaning the baby cannot eat by mouth), and polyhydramnios (excess amniotic fluid), clenched hands, choroid plexus cysts (a pocket of fluid on the brain that is not problematic in itself but may be a marker for Trisomy 18), rocker bottom feet, and delayed growth, micrognathia (small jaw), low-set ears, and a strawberry-shaped head, as well as severe developmental delays.

Helpful Links

www.soft.org.uk - Soft are a support organisation for Trisomy 18 & 13 in the UK 

www.trisomy18.org - This is the main site for support & research about Trisomy 18 and is worldwide. 

www.tcf.org.uk  - This is the website for compassionate friends who are based in the UK to help bereaved parents and their families after a child dies. 

www.uk-sands.org - Sands UK are a support organisation for anyone who has lost a baby, stillbirth or in the neonatal period.

www.everylifecounts.ie - A place where parents can share their memories, their stories, their love and their pain; where their children are remembered and cherished; and where we acknowledge that every life counts.

www.counselling-directory.org.uk - Counselling Directory is a confidential service that encourages those in distress to seek help. The directory contains information on many different types of distress, as well as articles, news, and events. To ensure the professionalism of our website, all counsellors have provided us with qualifications and insurance cover or proof of membership with a professional body.

Ffions Gift - Their first aim is to raise as much awareness of Edwards Syndrome as possible as well as financially helping families in Wales that have sadly suffered a loss by helping to fund a NIFTY / NIPT test during pregnancy with a rainbow baby.
​For more information please head to their Facebook Page - https://www.facebook.com/ffionsgift18 

 

Resources

The resources below have been provided to Emily's Star by John Carey.