Down syndrome is a genetic condition caused by the presence of an extra copy of chromosome 21, leading to characteristic physical features, developmental delays, and an increased risk of certain health problems. It is the most common chromosomal condition diagnosed in children.
🌍 What It Is
- Cause: Down syndrome results from an abnormal cell division that produces an extra full or partial copy of chromosome 21.
- Types:
- Trisomy 21 (≈95% of cases): All cells have three copies of chromosome 21.
- Translocation Down syndrome (≈3%): Extra chromosome 21 material is attached to another chromosome.
- Mosaic Down syndrome (≈2%): Some cells have three copies of chromosome 21, others have the usual two.
🔑 Characteristics
- Physical Features: Flattened facial profile, upward-slanting eyes, small ears, short neck, single crease across the palm, shorter stature.
- Developmental Delays: Slower progression in speech, motor skills, and learning milestones.
- Intellectual Disability: Usually mild to moderate, with variability among individuals.
- Associated Health Conditions:
- Congenital heart defects (≈50% of cases).
- Digestive system anomalies.
- Increased risk of leukemia, thyroid disorders, hearing and vision problems.
- Higher likelihood of Alzheimer’s disease at an earlier age.
📚 Social & Medical Significance
- Prevalence: About 5,700 babies are born with Down syndrome each year in the U.S..
- Life Expectancy: Improved dramatically in recent decades—from ~25 years in 1983 to ~60 years today.
- Support & Intervention: Early therapies (speech, occupational, physical) and inclusive education greatly improve quality of life.
- Community Resources: Organizations like the National Down Syndrome Society (NDSS) and GiGi’s Playhouse provide advocacy, education, and family support.
✨ Summary
Down syndrome is caused by an extra chromosome 21, leading to distinctive features, developmental delays, and health risks. With early intervention, medical care, and social support, individuals with Down syndrome can live long, fulfilling lives.
