Trisomy 18 Syndrome

Key Features

• Incidence is about 1:4000 live births

• Ratio of affected males to females is approximately 1:3

• Characterized by

  • Prenatal and postnatal growth retardation, which is often severe

  • Hypertonicity

• Complications are related to associated anomalies

• Death is often caused by heart failure or pneumonia and usually occurs in infancy or early childhood

• Small percentage reach adulthood; usually show significant cognitive disabilities

• A support group for families is called SOFT (see http://www.trisomy.org/)

Clinical Findings

• Small for gestational age

• Dysmorphic features including a characteristic facies and extremities (overlapping fingers and rocker-bottom feet)

• Congenital heart disease (often ventricular septal defect or patent ductus arteriosus)

Diagnosis

• Rapid confirmation of suspected trisomy 18 can be made by fluorescence in situ hybridization(FISH)

Treatment

• Supportive