Summary about Disease
Trisomy 21, also known as Down syndrome, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. This extra genetic material alters the course of development and causes characteristic physical features, intellectual disability, and associated medical conditions. It is one of the most common chromosomal abnormalities.
Symptoms
Symptoms of Trisomy 21 vary widely in severity from person to person. Common physical characteristics include:
Flattened facial features, especially the bridge of the nose
Small head
Short neck
Protruding tongue
Upward slanting palpebral fissures (eyes)
Unusually shaped or small ears
Poor muscle tone (hypotonia)
Short height
Single crease in the palm of the hand (Simian crease)
Small hands and feet Associated medical conditions can include:
Congenital heart defects
Hearing loss
Vision problems
Sleep apnea
Thyroid disorders
Increased risk of certain infections
Increased risk of leukemia Cognitive and developmental delays are also common, ranging from mild to severe intellectual disability.
Causes
Trisomy 21 is caused by an error in cell division called nondisjunction. This results in an embryo having three copies of chromosome 21 instead of the usual two. There are three types of Trisomy 21:
Trisomy 21 (Nondisjunction): This accounts for about 95% of cases. The individual has three separate copies of chromosome 21 in all cells.
Translocation: In about 4% of cases, part of chromosome 21 becomes attached (translocated) to another chromosome before or at conception.
Mosaicism: This occurs when nondisjunction of chromosome 21 takes place in one of the initial cell divisions after fertilization. Individuals with mosaic Down syndrome have some cells with an extra copy of chromosome 21 and some cells with the typical two copies. Parental age, specifically maternal age, is a known risk factor for Trisomy 21 (nondisjunction type).
Medicine Used
There is no cure for Trisomy 21, and no specific medication directly treats the chromosomal abnormality. Medical treatment focuses on managing the associated medical conditions and symptoms. This can include:
Heart Defects: Surgery and medications to manage heart problems.
Infections: Antibiotics for bacterial infections.
Thyroid Problems: Thyroid hormone replacement therapy.
Vision Problems: Glasses, surgery.
Hearing Loss: Hearing aids, surgery.
Developmental Delays: Early intervention programs, speech therapy, occupational therapy, physical therapy, and educational support.
Is Communicable
Trisomy 21 is not communicable. It is a genetic disorder caused by a chromosomal abnormality and cannot be spread from person to person.
Precautions
Since Trisomy 21 is not communicable, typical precautions to prevent the spread of infectious diseases are not relevant. However, people with Trisomy 21 may be more susceptible to certain infections due to immune system differences. Therefore, it's important to:
Ensure they receive all recommended vaccinations.
Practice good hygiene (handwashing) to prevent infections.
Monitor for signs of illness and seek medical attention promptly.
How long does an outbreak last?
Trisomy 21 is not caused by an infection and is not a type of disease that has outbreaks. The question does not apply.
How is it diagnosed?
Trisomy 21 can be diagnosed during pregnancy or after birth.
Prenatal Screening: These tests estimate the risk of a fetus having Trisomy 21. They include blood tests and ultrasound exams. Examples: Combined first trimester screening, quad screen, cell-free DNA testing (NIPT).
Prenatal Diagnostic Tests: These tests can confirm whether a fetus has Trisomy 21. They involve taking a sample of amniotic fluid (amniocentesis) or placental tissue (chorionic villus sampling - CVS).
Postnatal Diagnosis: After birth, Trisomy 21 is typically diagnosed based on the baby's physical characteristics. A chromosomal analysis (karyotype) can confirm the diagnosis.
Timeline of Symptoms
The timeline of symptoms varies widely, but generally follows this pattern:
Prenatal: Detection possible via screening tests.
At Birth: Noticeable physical characteristics (e.g., flattened face, poor muscle tone).
Infancy: Developmental delays become apparent (e.g., slower to roll over, sit, crawl). Increased risk of heart defects, feeding difficulties, and infections.
Childhood: Continued developmental delays in speech, language, and motor skills. Learning challenges become more evident. Monitoring and management of associated medical conditions.
Adolescence and Adulthood: Ongoing support for independent living skills, vocational training, and social integration. Monitoring for age-related health concerns.
Important Considerations
Early Intervention: Early intervention programs (physical therapy, occupational therapy, speech therapy) are crucial for maximizing a child's potential.
Individualized Education: Children with Down syndrome benefit from individualized education programs (IEPs) tailored to their specific needs.
Medical Care: Regular check-ups with specialists are essential to manage associated medical conditions.
Support Systems: Families benefit greatly from support groups and organizations dedicated to Down syndrome.
Quality of Life: With appropriate support and care, individuals with Down syndrome can live fulfilling lives, participate in their communities, and achieve their full potential.