Edwards syndrome

Overview

Edwards syndrome, also known as trisomy 18, is a rare but serious genetic disorder caused by the presence of an extra copy of chromosome 18. This condition leads to severe developmental delays, congenital anomalies, and growth problems. It affects approximately 1 in 5,000 live births and is the second most common trisomy after Down syndrome (trisomy 21). Edwards syndrome occurs more often in females than males and is associated with a high rate of miscarriage and infant mortality. Despite the severe prognosis, some children with the condition can live beyond infancy with supportive care.

Causes

Edwards syndrome is caused by an extra (third) copy of chromosome 18 in some or all of the body’s cells. This genetic abnormality interferes with normal development and function. The condition can occur in three forms:

• Full trisomy 18: All cells have an extra chromosome 18 (most common and severe form).

• Mosaic trisomy 18: Only some cells have the extra chromosome; symptoms may be milder.

• Partial trisomy 18: Only a portion of the chromosome is extra; symptoms vary based on which genes are involved.

Most cases are not inherited and occur as a random event during the formation of reproductive cells. The risk increases with maternal age.

Symptoms

Edwards syndrome affects many parts of the body and causes a wide range of physical and developmental issues. Common symptoms and features include:

• Low birth weight and slow growth before and after birth

• Severe intellectual disability and developmental delays

• Clenched fists with overlapping fingers

• Rocker-bottom feet (rounded soles)

• Microcephaly (small head) and prominent back of the head (occiput)

• Small jaw and mouth (micrognathia)

• Low-set, malformed ears

• Congenital heart defects (e.g., ventricular septal defect)

• Feeding difficulties and failure to thrive

• Kidney abnormalities

• Breathing problems or apnea

• Spinal defects such as scoliosis or spina bifida

Diagnosis

Diagnosis of Edwards syndrome can occur before or after birth. Prenatal screening and diagnostic tests include:

• First-trimester screening: Blood tests and ultrasound (nuchal translucency) to assess risk

• Non-invasive prenatal testing (NIPT): Analyzes fetal DNA in the mother’s blood to detect trisomy 18

• Diagnostic tests:

  • Chorionic villus sampling (CVS): Performed around 10–13 weeks

  • Amniocentesis: Usually done between 15–20 weeks to examine fetal chromosomes

After birth, diagnosis is confirmed by a physical examination and a karyotype (chromosomal analysis) from a blood sample.

Treatment

There is no cure for Edwards syndrome, and treatment focuses on managing symptoms and improving quality of life. Care plans depend on the severity of the condition and the family's goals. Treatment options include:

• Supportive care: Feeding assistance, respiratory support, and temperature regulation for newborns

• Management of heart defects: Some may require surgery if the child’s condition allows

• Multidisciplinary approach: Involving pediatricians, cardiologists, neurologists, nutritionists, and palliative care teams

• Physical and occupational therapy: To enhance mobility and development in long-term survivors

• Palliative and hospice care: May be appropriate for families prioritizing comfort and quality of life

Prognosis

The prognosis for Edwards syndrome is generally poor. Many affected fetuses do not survive to birth, and of those who are born alive, more than half die within the first week. Approximately 5–10% of children live beyond their first year, typically with severe disabilities. Children with mosaic or partial forms may live longer and have less severe symptoms. While long-term survival is rare, a small number of children with medical support and therapies have reached school age and beyond.