Down Syndrome: An Overview

 

Down syndrome, also known as trisomy 21, is a genetic condition caused by the presence of an extra copy of chromosome 21. This additional genetic material affects physical development and intellectual ability, though individuals with Down syndrome can lead full, meaningful lives with the right support.

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Key Characteristics

• Extra Chromosome:
  Individuals with Down syndrome have 47 chromosomes instead of the typical 46, due to an extra copy of chromosome 21.

• Physical Features:
  Common physical traits may include:

  • A flattened facial profile

  • Upward slanting eyes

  • A short neck

  • Small hands and feet

  • A single crease across the palm (in some cases)

• Developmental Delays:
  Children may reach milestones like walking and talking later than their peers, but progress is still achievable with support.

• Cognitive Differences:
  Most people with Down syndrome have mild to moderate intellectual disability, with learning styles that benefit from visual and hands-on approaches.

• Potential Health Concerns:
  Some individuals may be affected by:

  • Congenital heart defects

  • Hearing or vision problems

  • Thyroid conditions

  • Low muscle tone

  • Increased risk of infections or autoimmune disorders

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Types of Down Syndrome

1. Trisomy 21 (About 95% of cases):
   Every cell has three copies of chromosome 21.

2. Translocation Down Syndrome (About 3–4%):
   A part or all of chromosome 21 becomes attached to another chromosome.

3. Mosaic Down Syndrome (About 1–2%):
   Some cells have the usual two copies of chromosome 21, while others have three.

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Diagnosis and Support

• Prenatal Diagnosis:
  Screening tools such as blood tests and ultrasound can identify a risk, while amniocentesis or chorionic villus sampling (CVS) can confirm the diagnosis.

• Postnatal Diagnosis:
  Characteristic features at birth may raise suspicion, confirmed through a karyotype test (chromosome analysis).

• Support and Intervention:

  • Early intervention programs

  • Speech, occupational, and physical therapy

  • Special education and inclusive classrooms

  • Community resources and support groups

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Life Expectancy and Quality of Life

With advances in healthcare, the life expectancy of people with Down syndrome has increased significantly — often reaching 60 years or more.

Many individuals:

• Live independently or semi-independently

• Participate in employment, education, and volunteer work

• Enjoy friendships, relationships, and community life