What is Down Syndrome?

Down Syndrome is a genetic condition caused by the presence of an extra copy of chromosome 21. Instead of having the usual two copies, individuals with Down Syndrome have three copies (Trisomy 21).

  • Incidence: About 1 in every 700 live births worldwide.
  • Cause: Usually a random event during the formation of reproductive cells (egg or sperm) or in early embryo development.
  • Risk Factor: Risk increases with maternal age, especially over 35 years old.

Key Characteristics

Common physical traits include:

  • Flattened facial profile and small nose
  • Upward slanting eyes with epicanthal folds
  • Small ears
  • Short neck
  • Single crease across the palm (simian crease)
  • Short stature and low muscle tone (hypotonia) in infancy

Symptoms and Health Concerns

Cognitive Development

  • Mild to moderate intellectual disability (IQ typically between 35–70)
  • Delayed speech and motor development

Medical Conditions

  • Congenital heart defects (in ~50% of cases, e.g., atrioventricular septal defect)
  • Hearing loss due to frequent ear infections
  • Vision problems (cataracts, refractive errors)
  • Thyroid disorders (especially hypothyroidism)
  • Higher risk of leukemia
  • Higher risk of early-onset Alzheimer’s disease

Diagnosis

Prenatal Screening

  • Non-Invasive Prenatal Testing (NIPT) to detect extra chromosome 21
  • First trimester combined screening (ultrasound + maternal blood test)
  • Confirmatory tests: Amniocentesis or Chorionic Villus Sampling (CVS)

Postnatal Diagnosis

  • Physical examination + karyotype analysis to confirm the presence of Trisomy 21.

Prevention & Risk Reduction

While Down Syndrome cannot be completely prevented, certain technologies can reduce the risk of having an affected child:

  • Preimplantation Genetic Testing for Aneuploidy (PGT-A) during IVF
    • Detects embryos with extra chromosome 21 before implantation
    • Only chromosomally normal embryos are transferred
  • Prenatal genetic screening for early detection and informed decision-making

Management

There is no cure for Down Syndrome, but early medical care and support can improve quality of life:

  • Early intervention programs for speech, physical, and occupational therapy
  • Cardiac surgery for congenital heart defects
  • Regular hearing, vision, and thyroid checks
  • Inclusive education and social support for cognitive development
  • Healthy lifestyle to reduce risk of obesity and related conditions