What is Edwards Syndrome (Trisomy 18)?

Edwards Syndrome is a chromosomal disorder caused by the presence of an extra chromosome 18 in a person’s cells. Instead of the typical 46 chromosomes, affected individuals have 47 chromosomes.

  • Incidence: About 1 in 5,000 live births
  • Cause: Nondisjunction during the formation of reproductive cells, leading to an embryo with three copies of chromosome 18
  • Variants:
    • Full Trisomy 18 – extra chromosome present in every cell (most severe)
    • Mosaic Trisomy 18 – extra chromosome present in some cells (milder symptoms)
    • Partial Trisomy 18 – only part of chromosome 18 is duplicated

Key Characteristics

  • Small head size (microcephaly)
  • Low birth weight
  • Clenched fists with overlapping fingers
  • Rocker-bottom feet
  • Small jaw and mouth (micrognathia)
  • Heart defects (such as ventricular septal defect)
  • Abnormal ears and facial features

Symptoms and Health Concerns

Physical

  • Severe developmental delays
  • Growth restriction before and after birth
  • Feeding difficulties due to weak muscle tone
  • Structural organ defects (especially heart, brain, and kidneys)

Neurological

  • Seizures
  • Severe intellectual disability
  • Poor response to stimuli

Medical Risks

  • High mortality rate; many affected infants do not survive beyond the first year
  • Chronic respiratory problems in survivors
  • Recurrent infections

Diagnosis

Prenatal

  • Screening tests: NIPT (Non-Invasive Prenatal Testing), first-trimester combined screening (ultrasound + blood test)
  • Diagnostic tests: Amniocentesis or CVS to confirm extra chromosome 18

Postnatal

  • Physical examination for characteristic features
  • Karyotype analysis to confirm diagnosis

Prevention & Risk Reduction

Edwards Syndrome cannot be prevented naturally. However, Preimplantation Genetic Testing for Aneuploidy (PGT-A) during IVF can detect embryos with normal chromosome 18, reducing the risk of conceiving a child with Trisomy 18.

Management

  • Supportive care to manage feeding, breathing, and infections
  • Heart surgery in selected cases (if feasible)
  • Early intervention programs for developmental support
  • Palliative care for severe cases