Short answer · Medically reviewed summary · Last updated: 2026-04-07
Edwards syndrome, also known as Trisomy 18, is a rare chromosomal condition caused by the presence of an extra copy of chromosome 18 in all or some of the body's cells. This genetic variation significantly disrupts normal development, often leading to severe intellectual disabilities, growth delays, and complex physical health challenges affecting multiple organ systems. What causes Edwards syndrome? The primary cause of Edwards syndrome is a genetic error occurring during the formation of reproductive cells (eggs or sperm) or during early embryonic development.
1 people with Edwards syndrome have shared their first-person experience on this question at DiseaseMaps.
What is Edwards syndrome
What is Edwards syndrome? Plain-language, medically reviewed definition plus the lived reality told by patients.
Edwards syndrome, also known as Trisomy 18, is a rare chromosomal condition caused by the presence of an extra copy of chromosome 18 in all or some of the body's cells. This genetic variation significantly disrupts normal development, often leading to severe intellectual disabilities, growth delays, and complex physical health challenges affecting multiple organ systems.
What causes Edwards syndrome?
The primary cause of Edwards syndrome is a genetic error occurring during the formation of reproductive cells (eggs or sperm) or during early embryonic development. Typically, humans have 23 pairs of chromosomes, but individuals with Edwards syndrome have three copies of chromosome 18 instead of the usual two. This extra genetic material interferes with the body’s ability to follow standard developmental blueprints, which is why the condition impacts so many different areas of physical and cognitive health.
How does Edwards syndrome affect the body?
Because chromosome 18 contains a vast amount of genetic information, the extra copy associated with Edwards syndrome impacts nearly every organ system. Symptoms are highly variable, but common clinical features often include:
- Cardiac anomalies: Most infants are born with congenital heart defects, such as ventricular septal defects or patent ductus arteriosus.
- Structural differences: These may include a small head (microcephaly), low-set ears, a small jaw (micrognathia), and clenched fists with overlapping fingers.
- Growth and Development: Children typically experience severe intrauterine growth restriction (IUGR) and significant developmental delays.
- Organ involvement: Complications frequently arise in the kidneys, gastrointestinal tract, and respiratory system.
What are the different types of Edwards syndrome?
The severity of the condition often depends on the specific genetic subtype, which is determined by how the extra chromosome is distributed:
- Full Trisomy 18: The most common form, where every cell in the body contains an extra chromosome 18.
- Mosaic Trisomy 18: Only some cells contain the extra chromosome, which can sometimes lead to a milder presentation of symptoms.
- Partial Trisomy 18: Only a segment of the extra chromosome 18 is present, rather than the entire chromosome.
How common is Edwards syndrome?
Edwards syndrome is estimated to occur in approximately 1 in every 5,000 to 8,000 live births. While the condition can occur in any pregnancy, the risk increases with maternal age. Because of the severe health challenges associated with Edwards syndrome, many pregnancies do not reach full term. Within the DiseaseMaps.org community, 108 people have connected to share their unique experiences and support one another while navigating the complexities of this diagnosis.
What differentiates Edwards syndrome from other conditions?
While Edwards syndrome shares some features with other chromosomal disorders like Down syndrome (Trisomy 21) or Patau syndrome (Trisomy 13), it is clinically distinct. The specific pattern of physical features—particularly the characteristic clenched hand position and the specific types of cardiac and renal malformations—helps clinicians distinguish Edwards syndrome from other trisomies through genetic testing, such as karyotyping or chromosomal microarray analysis.
Next steps
- Consult with a clinical geneticist to confirm the diagnosis and discuss the specific genetic subtype.
- Work with a multidisciplinary medical team, including pediatric cardiologists, neurologists, and palliative care specialists.
- Connect with the 108 members of the DiseaseMaps.org community to find peer support and shared resources.
- Seek guidance from genetic counselors to understand the recurrence risks for future pregnancies.
Medical disclaimer: This information is for educational purposes only and should not replace professional medical advice, diagnosis, or treatment from a qualified healthcare provider.
References
- NIH Genetic and Rare Diseases (GARD) Information Center: Trisomy 18.
- Orphanet: Edwards syndrome (ORPHA:3404).
- Online Mendelian Inheritance in Man (OMIM): Trisomy 18 (#176000).
- SOFT (Support Organization For Trisomy 18, 13, and Related Disorders).
Most cases of Edwards syndrome occur due to problems during the formation of the reproductive cells or during early development. The rate of disease increases with the mother's age. Rarely cases may be inherited from a person's parents.Occasionally not all cells have the extra chromosome, known as mosaic trisomy, and symptoms in these cases may be less severe. Ultrasound can increase suspicion for the condition, which can be confirmed by amniocentesis.
Treatment is supportive.After having one child with the condition, the risk of having a second is typically around one percent.It is the second-most frequent condition due to a third chromosome at birth, after Down syndrome.
Edwards syndrome occurs in around one in 5,000 live births. Some studies suggest that more babies that survive to birth are female. Many of those affected die before birth. Survival beyond a year of life is around 5–25%.It is named after John Hilton Edwards, who first described the syndrome in 1960.
Posted Feb 18, 2018 by Federica 3600
