Trisomy 18, also known as Edwards syndrome, is a rare genetic disorder in which a person has an extra copy of chromosome 18 in some or all of their cells. Various organs and tissues in the body are affected by this extra chromosome, leading to physical and mental abnormalities. Babies with trisomy 18 rarely survive beyond their first year of life, and those who do face severe challenges.
There is no inheritance of trisomy 18, but rather a random error occurs during the development of the egg or sperm cells, or in the early stages of the embryo. Instead of the normal two copies of chromosome 18, this error causes a third copy to appear in some or all of the cells. There is no clear explanation for why this error occurs, but older mothers, particularly those over 35, are more likely to experience it.
The symptoms of trisomy 18 vary depending on how many cells have the extra chromosome and which organs are affected. However, some common features include:
Low birth weight and slow growth
Small head and jaw, and abnormal facial features
Heart defects and other organ malformations
Clenched hands with overlapping fingers
Cleft lip and/or palate
Rocker-bottom feet or clubfoot
Hernias and intestinal problems
Severe intellectual disability and developmental delays
Feeding and breathing difficulties
Muscle and joint problems
During pregnancy, ultrasound findings such as growth restriction, heart defects, clenched hands, and other anomalies can indicate trisomy 18. A sample of amniotic fluid or the placenta can be tested for chromosomal abnormalities in order to confirm the diagnosis. Amniocentesis and chorionic villus sampling (CVS) are two procedures that carry a small risk of miscarriage.
Trisomy 18 is diagnosed after birth by examining the baby's physical characteristics and performing a blood test to identify the extra chromosome. This test is called karyotyping and can also tell how many cells have the extra chromosome.
The goal of trisomy 18 treatment is to provide comfort and care for the baby and the family, and to manage any medical complications that may arise. Treatment options include:
Surgery to correct life-threatening heart defects or other organ problems
Medications to treat seizures, infections, or other conditions
Feeding tubes or special formulas to provide adequate nutrition
Oxygen therapy or ventilators to assist with breathing
Physical therapy or orthotics to improve mobility and posture
Pain relief and hospice care to ease suffering
The decision to pursue any treatment should be made in consultation with the healthcare team and the family, taking into account the benefits and risks, as well as the baby's quality of life and prognosis.
Trisomy 18 cannot be prevented, as it is a random and unpredictable event. However, some factors that may reduce the risk of having a baby with trisomy 18 include:
Having a healthy lifestyle before and during pregnancy, such as avoiding smoking, alcohol, and drugs, and taking prenatal vitamins
Having regular prenatal check-ups and screenings to monitor the health and development of the baby
Considering genetic counseling and testing if there is a family history of chromosomal disorders or if the mother is older than 35 years of age
In addition to affecting both the baby and the family, trisomy 18 is a serious and life-threatening condition. Support and guidance are important from both the healthcare team and from other sources, such as support groups, counselors, and religious leaders. Each family has to make the best decisions for themselves and their baby, based on their values, beliefs, and circumstances. There is no right or wrong way to cope with trisomy 18.
