Most common pattern of human malformation
• Genetics
- Full trisomy 21-94%; risk of recurrence 1%
- Risk of nondisjunction increases with advancing maternal age (more than
doubles after 30 years old)
• Findings
- Upward slanting palpebral fissures; speckling of iris (Brushfield spots); inner
epicanthal folds; myopia, strabismus
- Small stature
- Mouth open with tongue protrusion
- Late fontanel closure; mild microcephaly
- Short neck, flat occiput
- Short metacarpals and phalanges; simian crease
- Hypotonia
- Hearing loss (sensorineural, conductive, and mixed)
- Primary gonadal deficiency
- Cardiac anomaly-ECD > VSD > PDA, ASD; also MVP
- Gastrointestinal anomalies: tracheoesophageal fistula, duodenal atresia
- Atlanto-axial instability
- Hypothyroidism
Acute lymphocytic leukemia
- Mental retardation
• Natural history
- Major cause for early mortality is congenital heart disease
- Higher mortality from respiratory disease and infection than rest of population
- Muscle tone improves with age
- Rate of development slows with age
- Early onset of Alzheimer disease
Note
Cardiac Definition of
Abbreviations
ASD: atrial septal defect
ECD: endocardial cushion
defect
MVP: mitral valve prolapse
PDA: patent ductus arteriosus
TOF: tetralogy of Fallot
VSD: ventricular septal defect
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Second most common pattern of human malformation
