Related Subjects:
|Dementias
The condition is typically caused by a nondisjunction event, where the 21st chromosome fails to separate during egg or sperm development, leading to an embryo with three copies of chromosome 21 instead of the usual two.
Aetiology
- Non-disjunction (94%): Linked to maternal age, all cells have three copies of chromosome 21.
- Mosaicism (2%): Some cells have trisomy 21, while others do not, leading to milder symptoms.
- Robertsonian Translocation (4%): Part of chromosome 21 is attached to another chromosome, potentially hereditary.
Clinical Features
- Distinct facial features: flattened profile, small ears and mouth
- Epicanthic folds: skin folds at the inner corner of the eyes
- Single palmar crease, Brushfield spots, intellectual disability
- Short stature, short neck
- Hypotonia (low muscle tone), flat occiput, oval face
- Congenital heart defects: atrial septal defects, endocardial cushion defects, patent ductus arteriosus, Fallot's tetralogy
- Gastrointestinal anomalies: duodenal atresia, Hirschsprung's disease
Long-Term Considerations
- Increased risk of leukaemia and other cancers
- Endocrine disorders: hypothyroidism, coeliac disease
- Neurological issues: epilepsy, Alzheimer's disease
- Higher susceptibility to infections, respiratory, hearing, and vision problems
- Gastrointestinal complications: duodenal atresia, Hirschsprung's disease
- Obesity and related health concerns
Investigations
- Prenatal Screening: Blood tests and ultrasound to assess risk, with diagnostic confirmation via chorionic villus sampling (CVS) or amniocentesis.
- Postnatal Testing: Karyotyping to confirm diagnosis.
- Ultrasound Findings: At 18 weeks, signs such as nuchal thickening, atrioventricular septal defects, or a "double bubble" indicating duodenal atresia may suggest Down's syndrome.
Management
- Supportive care for intellectual disabilities, including special education and therapy for speech and motor development.
- Medical management of congenital heart defects, respiratory issues, thyroid problems, and other associated conditions.
- Regular monitoring for and management of potential complications such as obesity, infections, and neurological disorders.
- Enhanced quality of life through specialized education, support services, and community inclusion.
- Increased life expectancy with advances in medical care, with many individuals living into their 60s or beyond.