Trisomy 18 (Edwards Syndrome)

Overview

Certainly! Here’s a clear and detailed overview of Trisomy 18, also known as Edwards Syndrome:

🧬 Trisomy 18 (Edwards Syndrome)

Overview

Trisomy 18, or Edwards Syndrome, is a genetic disorder caused by the presence of an extra copy of chromosome 18. This extra chromosome affects how the body develops, often leading to severe intellectual and physical disabilities.

📌 Cause

• Normally, humans have 46 chromosomes (23 pairs). In Trisomy 18, there are three copies of chromosome 18 instead of two.
• This condition usually occurs sporadically (not inherited) due to a random error in cell division (nondisjunction).
• There are three types:
  1. Full Trisomy 18 (most common): Every cell has the extra chromosome.
  2. Mosaic Trisomy 18: Only some cells have the extra chromosome.
  3. Partial Trisomy 18: Only a part of chromosome 18 is extra or attached to another chromosome.

🧒 Who Is Affected?

• Occurs in about 1 in 5,000 live births.
• More common in girls than boys.
• Risk increases with maternal age.
• Many affected pregnancies result in miscarriage or stillbirth.

🩺 Symptoms

Trisomy 18 affects many organ systems. Common signs include:

Physical Features:

• Small head and jaw (microcephaly, micrognathia)
• Low-set ears
• Clenched fists with overlapping fingers
• Rocker-bottom feet
• Heart defects (very common)
• Growth restriction (low birth weight)

Developmental:

• Severe intellectual disability
• Feeding difficulties
• Delayed milestones

Medical Issues:

• Breathing problems
• Kidney malformations
• Spinal and limb abnormalities
• High risk of infections

🔍 Diagnosis

Before Birth (Prenatal):

• Ultrasound: May detect abnormalities.
• Non-invasive prenatal testing (NIPT): Blood test that analyzes fetal DNA.
• Amniocentesis or chorionic villus sampling (CVS): Confirms diagnosis by analyzing chromosomes.

After Birth:

• Physical exam and karyotype test (genetic test) confirm the diagnosis.

❤️ Prognosis

• High mortality rate:
  • Over 90% of affected infants do not survive beyond the first year.
  • Most die in utero or within the first weeks/months.
• A small number (especially those with mosaic or partial forms) may survive longer with significant disabilities.

💊 Treatment and Care

There is no cure. Management focuses on:

• Comfort and palliative care
• Treating specific complications (e.g., heart defects, feeding issues)
• Some families choose aggressive interventions, while others opt for supportive care only

👪 Support for Families

• Genetic counseling: Important for understanding recurrence risks.
• Emotional, psychological, and palliative care support is vital.
• Support organizations (e.g., SOFT – Support Organization for Trisomy) offer resources and connections.

🧠 Summary