Down Syndrome

DOWN SYNDROME

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📖 Definition

Down syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21, either completely or partially. Instead of the usual 46 chromosomes, individuals with Down syndrome have 47 chromosomes.

🔬 This additional genetic material affects normal physical and cognitive development.

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📊 Epidemiology

• Incidence: about 1 in 700 live births.

• It is the most common chromosomal abnormality compatible with life.

• More frequent in older mothers (>35 years), although most cases occur in younger mothers due to the higher birth rate in that age group.

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⚙️ Pathophysiology

Normally, a person inherits one chromosome 21 from each parent. In Down syndrome:

• In 95% of cases: trisomy 21 – three full copies of chromosome 21.

• In 4% of cases: translocation – part of chromosome 21 attaches to another chromosome.

• In 1% of cases: mosaicism – some cells have trisomy 21, others are normal.

📌 The extra genetic material leads to abnormal development of the brain, heart, muscles, and other systems.

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🧾 Causes and Risk Factors

Cause:

• A meiotic error during the formation of eggs or sperm, where chromosome 21 fails to separate properly (nondisjunction).

Risk Factors:

• Advanced maternal age (>35 years).

• Family history of translocation.

• Having previous children with Down syndrome.

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🚨 Symptoms

Physical signs:

• Flattened facial features

• Almond-shaped eyes with an upward slant

• Short neck

• Hypotonia (low muscle tone)

• Growth delay

• Broad hands with a single palmar crease

Cognitive:

• Mild to moderate intellectual disability

• Speech and language delay

• Motor development delay

Common associated conditions:

• Congenital heart defects (about 50% of cases)

• Gastrointestinal anomalies (e.g., duodenal atresia)

• Hearing and vision problems

• Immune deficiencies

• Increased risk of childhood leukemia

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🔍 Diagnosis

1. During pregnancy (prenatal diagnosis):

• First-trimester screening:

• Ultrasound (nuchal translucency)

• Blood tests (β-hCG, PAPP-A)

• → These estimate the risk.

• Definitive diagnosis:

• Chorionic villus sampling (CVS) or

• Amniocentesis

• These allow direct karyotype analysis of fetal cells to confirm trisomy 21.

2. After birth:

• Clinical signs at birth may suggest Down syndrome.

• Karyotype testing confirms the diagnosis by identifying the extra chromosome.

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💊 Treatment

There is no cure for Down syndrome. Management is supportive and multidisciplinary, focused on treating symptoms and improving quality of life.

Common treatments and medications:

1. Levothyroxine

• 👉 Used to treat congenital hypothyroidism, which is common in Down syndrome.

• 💊 It replaces the deficient thyroid hormone.

2. Diuretics / ACE inhibitors / Cardiac surgery

• 👉 For managing congenital heart defects.

3. Antibiotics and vaccines

• 👉 To prevent or treat infections due to weakened immunity.

4. Antiepileptic drugs or ADHD medications, if these conditions are present.

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🏥 Nursing Care

Nurses play a critical role in:

• 👨‍👩‍👧 Supporting the family and caregivers emotionally and practically.

• 🧠 Monitoring development (motor, cognitive, and social).

• 💊 Administering medications (e.g., thyroid hormones, cardiac drugs).

• 💉 Monitoring vital signs, especially in heart disease.

• 👂🦷 Encouraging regular vision, hearing, and dental checks.

• 🧼 Educating about hygiene and infection prevention.

• 🧘‍♂️ Promoting autonomy and daily life skills.

• 📚 Coordinating school and community support.

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🛡️ Prevention

Down syndrome cannot be completely prevented, but risk assessment and early diagnosis are possible:

1. Genetic counseling:

• For couples at higher risk (e.g., advanced maternal age, family history).

2. Prenatal screening and diagnosis:

• Blood tests, ultrasounds, and

• Non-invasive prenatal testing (NIPT) – analyzes fetal DNA in the mother’s blood.

3. Younger maternal age:

• Risk increases significantly with maternal age.