Down syndrome is a chromosomal condition due to mutations relating to chromosome 21 resulting in intellectual disability and physical abnormalities. It is diagnosed by genetic testing and treated based on manifestations.
Pathophysiology
Possible Gene Mutations
- Translocation of chromosome 21 to chromosome 14 t(14;21)
- Translocation t(21;22)
Contextual Factors
- 6000 babies/ years
- Previous children with Down syndrome
- Parent with Down syndrome
- Pregnant mother > 34 years old
Clinical Manifestation
Pediatric/ At Birth
Cardiac
- Ventricular septal defect
- Atrioventricular canal (endocardial cushion)
Endocrine
- Hypothyroidism
- Diabetes
GI
- Duodenal atresia or stenosis
- Hirschsprung disease
- Celiac disease
HEENT
- Ophthalmic disorders: congenital cataracts, glaucoma, strabismus, refractive errors
- Hearing loss
- Anomalous ears
- Recurrent otitis media
- Flat facial profile
- Excessive skin at nape of the neck
- Slanted palpebral fissures
Heme/Onc
- Thrombocytopenia
- Neonatal polycythemia
- Transient myelodysplastic disorder
- Acute megakaryoblastic leukemia
- Acute lymphocytic leukemia
MSK
- Hyperflexibility of joints
- Dysplasia of pelvis
- Dysplasia of mid-phalanx of fifth finger
- Transverse palmar (Simian) crease
Neuro
- Hypotonia
- Poor Moro reflex
- Cognitive impairement
- Mild (IQ 50 - 75)
- Severe (IQ 20 - 35)
- Gross motor and language delays
- Autistic behaviour
Respiratory
- Obstructive sleep apnea
Adult
- Reduced height
- Risk of obesity
Cardiac
- Mitral valve prolapse
- Aortic regurgitation
Neuro
- Early-onset Alzheimer’s
Diagnosis
Prenatal Detection
- Fetal ultrasonography
- Maternal serum screening
- Noninvasive prenatal screening
Prenatal Diagnosis
- Prenatal chorionic villus sampling
- Amniocentesis w/ karyotyping
Neonatal Diagnosis
- Postnatal karyotyping
Treatment
- No cure
- Genetic counseling for the family
Symptom Treatment
- Cardiac: surgical repair
- Hypothyroidism: thyroid hormone replacement
Support
- Social support
- Educational accomodations
Screenings
- Down syndrome growth chart
- Atlantoaxial instability screening (if suspicious)
- Celiac disease screening (if suspicious)
| Visit | Screenings |
|---|---|
| Prenatal | Echocardiogram |
| Birth | Echocardiogram, thyroid screening, hearing evaluation |
| 6 months old | Thyroid screening, hearing evaluation, ophthalmology evaluation |
| 12 months old | Thyroid screening |
| 4 years old | Sleep study (for OSA) |
| Every 6 months | Hearing evaluation (until normal) |
| Annual | Thyroid screening, hearing evaluation (after normal), ophthalmology screening (< age 5) |
| Biennial | Ophthalmology evaluation (< age 13) |
| Triennial | Opthalmology evaluation (< age 21) |