Down Syndrome: Clinical Features, Health Supervision & Life Potential

Trisomy 21: A Variable Phenotype

Down syndrome (DS) results from an extra copy of chromosome 21 (95% free trisomy, 3–4% Robertsonian translocation, 1–2% mosaicism). Features vary widely.

Common Physical Features

• Face: Upward slanting palpebral fissures, epicanthal folds, flat nasal bridge, small ears, protruding tongue (relative macroglossia).
• Hands: Single palmar crease (simian), clinodactyly (5th finger), broad short hands.
• Growth: Short stature, brachycephaly, hypotonia (floppy infant).
• Other: Brushfield spots (iris), wide gap 1st-2nd toes (sandal gap).

Developmental Profile

• Global delays: Motor (sit 11m, walk 26m avg), speech (expressive > receptive), cognition (IQ 30–70, mean ~50).
• Strengths: Visual learning, social engagement, imitation, gesture use.
• Early intervention (PT, OT, ST) from birth → maximizes potential.

Medical Comorbidities (Surveillance Essentials)

System	Conditions	Screening/Action
Cardiac	AVSD (40–50%), VSD, ASD, TOF	Echo at diagnosis; surgery often <6m
GI	Duodenal atresia, Hirschsprung, celiac (5–15%), constipation	Abdominal XR if bilious emesis; celiac serology q1–2y
Endocrine	Hypothyroidism (15–30%), T1DM, obesity	TSH at birth, 6m, 12m, then annually
Hematologic	Transient myeloproliferative disorder (TMD) → AML risk; polycythemia	CBC at birth, monitor TMD
Sensory	Hearing loss (50–75% – conductive + SNHL), cataracts, refractive errors, strabismus	ABR at birth; audiology q6m; ophthalmology annually
Respiratory	Airway malacia, OSA (50–80%), aspiration, atlantoaxial instability (AAI)	Sleep study by 4y; C-spine XR if neuro signs
Immunologic	↑ infections, autoimmune (thyroid, celiac, alopecia)	Vaccines per schedule (live OK unless immunocompromised)

Health Supervision (AAP Guidelines)

• Age-specific checklists: growth (DS charts), development, labs, imaging, referrals.
• Transition to adult care (DS specialty clinics emerging).

Life Outcomes

• Life expectancy ~60 years (up from 25 in 1983).
• Many read, work, live semi-independently, form relationships.
• Inclusion, education, and family support are key determinants.

Each person with DS is unique. Focus on abilities, not just the diagnosis.