What is Edwards Syndrome (Trisomy 18)?

Edwards syndrome is a severe genetic disorder that can have significant health consequences for a baby. For expecting parents, having timely information about potential abnormalities is essential. Modern tests now allow early detection of this condition, giving parents the opportunity to make important decisions regarding the health and future of their child.

History and definition of Edwards syndrome

Edwards syndrome was first identified by British geneticist John Hilton Edwards in 1960. He detailed this disorder in newborns displaying specific physical abnormalities, including organ deformities and heart defects. The syndrome was named after him in recognition of his pioneering research in genetics. Since then, Edwards syndrome has been recognized as the second most common trisomy in humans, following Down syndrome (trisomy 21).

Edwards syndrome, also known as trisomy 18, occurs due to the presence of a third copy of chromosome 18, which severely disrupts normal fetal development. Babies with this condition often suffer from significant physical and intellectual disabilities. This includes organ malformations, stunted growth, and severe heart and kidney defects.

The syndrome arises from an error during cell division in the formation of the egg or sperm, known as meiosis, when chromosomes fail to separate properly. When the abnormal reproductive cell combines with a normal one, an embryo with three copies of chromosome 18 forms, resulting in Edwards syndrome. The risk of these errors increases with maternal age, especially after the age of 35.

Statistics and prevalence of Edwards syndrome

Edwards syndrome occurs in approximately 1 in every 6,000 pregnancies. It is more commonly diagnosed in girls, with up to 80% of cases involving female infants. Due to the severity of the associated health issues, many pregnancies result in miscarriage, and only a small percentage of babies survive beyond their first year.

Inherited trisomy vs. Random trisomy

In most cases, Edwards syndrome occurs randomly and is not inherited. This means there is no genetic factor predicting whether a baby will develop the condition. However, in rare instances, inherited forms of trisomy (partial trisomy) can occur, especially when one of the parents carries a balanced translocation, where a part of one chromosome is “attached” to another without causing excess genetic material in the parent.

Types of trisomy 18

There are three main variations of Edwards syndrome:

• Full Trisomy 18 – This is the most common and severe form. Every cell in the body has three copies of chromosome 18, which severely disrupts the normal development of all organs and systems. Babies with full trisomy 18 often suffer from serious heart, kidney, and respiratory problems, along with significant physical deformities. This form of the syndrome typically results in a very short life span, with only a small percentage of babies surviving beyond a few months.
• Mosaic Trisomy 18 – In this variation, only some cells carry the extra chromosome 18, while other cells are normal. This leads to milder symptoms compared to full trisomy 18. The severity and prognosis depend on how many cells are affected and which tissues they are present in. Babies with mosaic trisomy 18 often have a longer life expectancy and milder developmental delays, though they can still face significant health challenges.
• Partial Trisomy 18 – This form occurs when only a part of chromosome 18 is present in excess in the cells, rather than the entire chromosome. The severity of symptoms depends on which part of the chromosome is affected and how much extra chromosomal material is present. This variation can result in a wide range of symptoms, from mild to severe, but it is less common than full trisomy and mosaicism.

Symptoms of Edwards syndrome

Babies born with Edwards syndrome typically exhibit distinctive physical and developmental characteristics that are easily noticeable at birth:

• Low birth weight – Babies with trisomy 18 are often smaller than average.
• Abnormally shaped head – The head may be disproportionately small or have an unusual shape.
• Clenched fists and finger deformities – Fingers are often clenched into fists, with overlapping fingers.
• Heart defects – Up to 90% of babies are born with congenital heart defects, further complicating treatment.
• Kidney and lung problems – Underdeveloped organs, such as the kidneys and lungs, frequently cause respiratory issues.
• Malformations of internal organs – Babies may experience severe gastrointestinal problems, such as gastroesophageal reflux or malformations of the esophagus and kidneys.

Prognosis and treatment

Sadly, the prognosis for babies with Edwards syndrome is very poor. Around 50% of affected infants pass away within the first few months of life, and only a small percentage live to see their first birthday. The average life expectancy is between 5 and 10 days, with only 5-10% surviving beyond one year.

Treatment for Edwards syndrome is primarily palliative, focusing on relieving symptoms and ensuring the best possible quality of life. Although surgical interventions can be considered for heart or gastrointestinal issues, these rarely result in significant long-term improvements.

Surviving babies face numerous challenges, including severe intellectual disabilities, motor impairments, and ongoing health issues.

How is Edwards syndrome diagnosed

Edwards syndrome can be diagnosed during pregnancy through several types of prenatal tests that allow for early detection of chromosomal abnormalities. One of the most reliable tests is the NIPT (Non-Invasive Prenatal Test), which analyzes fetal DNA from the mother’s blood. These tests are completely safe for both the mother and the baby and can detect Edwards syndrome early in pregnancy.

• Prenatal BASIC Test: Detects trisomies 21, 18, 13 + determines the baby’s gender.
• Prenatal PLUS Test: Detects trisomies 21, 18, 13 + analyzes sex chromosomes + determines the baby’s gender.
• Prenatal EXPERT Test: Detects trisomies 21, 18, 13 + analyzes sex chromosomes + DiGeorge syndrome + determines the baby’s gender.
• Prenatal PREMIUM Test: Detects trisomies 21, 18, 13 + analyzes sex chromosomes + microdeletions + determines the baby’s gender.
• Prenatal ALL CHROMOSOMES Test: Analyzes all chromosomes, sex chromosomes, deletions, and microdeletions + determines the baby’s gender.
• Prenatal SPECIAL Test: Detects trisomies 21, 18, 13 + analyzes sex chromosomes + microdeletions + 100 hereditary diseases + determines the baby’s gender.
• Prenatal SPECIAL + SMA Test: Detects trisomies 21, 18, 13 + analyzes sex chromosomes + microdeletions + 100 monogenic diseases + SMA + determines the baby’s gender.
• Prenatal Next Kario Plus Test: Analyzes all chromosomes, sex chromosomes, deletions, and microdeletions + determines the baby’s gender + hereditary and non-hereditary diseases in the baby.
• Prenatal Next Kario Full Test: Comprehensive analysis of all chromosomes, sex chromosomes, deletions, and microdeletions + determines the baby’s gender + hereditary and non-hereditary diseases in the baby + 30 hereditary diseases in the parents.

Prenatal tests for Edwards syndrome are conducted using advanced NGS (Next Generation Sequencing) technology, providing parents with critical information about the condition of the fetus and allowing them to make informed decisions regarding the pregnancy.

The importance of prenatal testing

Early detection of Edwards syndrome can help parents make difficult decisions during pregnancy. Statistics show that in Europe, more than 90% of pregnancies are terminated when severe chromosomal abnormalities, such as trisomy 18, are identified in the early stages.

Prenatal testing provides accurate information about the fetus’s health without posing any risk to the mother or baby. This reduces uncertainty and offers a peace of mind during pregnancy. In the case of a positive result, genetic counseling assists parents in understanding the findings and exploring all available options, offering essential support for making informed decisions.

Prenatal support from IntroLab

For a safe and stress-free pregnancy, having reliable information and support is crucial. The prenatal tests offered by IntroLab enable early detection of Edwards syndrome and other genetic disorders, providing parents with a clear picture of the fetus’s condition. With our expert guidance and genetic counseling, you can make the best choices for yourself and your baby. Scheduling prenatal testing at IntroLab gives you peace of mind and security throughout your pregnancy, supported by a team of specialists who are with you every step of the way. Reach out to us today to ensure the most dependable care for your future.