Down Syndrome

CHAPTER 73

Down Syndrome

Introduction/Etiology/Epidemiology

• Down syndrome is a genetic disorder associated with intellectual disability and musculoskeletal, cardiovascular, endocrine, gastrointestinal, immune, and visual abnormalities (Box 73-1).

• It is caused by an additional chromosome 21. Chromosome 21 codes for type VI collagen; this abnormality results in generalized laxity.

• The most common chromosomal abnormality in the United States, it affects 1 in every 800 to 1,000 live births.

• Risk increases with maternal age from 1 in 2,000 at maternal age 20 years to 1 in 30 at maternal age 45 years.

• Common physical characteristics include microcephaly, epicanthal folds, hypotonia, short neck, flattened nasal bridge, single transverse palmar crease, shortened limbs, and a protruding tongue.

Box 73-1. Medical Concerns for Individuals With Down Syndrome

• Intellectual disability (varies)

• Obesity

• Obstructive sleep apnea

• Hearing loss

• Epilepsy

• Leukemia

• Musculoskeletal

— Atlantoaxial instability

— Joint instability/laxity

— Hypotonia

— Pes planus

— Scoliosis

• Cardiovascular

— Congenital heart defects (atrial septal defect, ventricular septal defect, atrioventricular septal defect, patent foramen ovale, patent ductus arteriosus, tetralogy of Fallot)

— Lower cardiovascular fitness level

• Endocrine

— Thyroid disease

• Gastrointestinal

— Tracheoesophageal fistula

— Duodenal atresia

— Annular pancreas

— Hirschsprung disease

— Anal atresia

— Umbilical hernia

• Visual

— Cataracts

— Severe refractive errors

Musculoskeletal Manifestations

• Ligamentous laxity increases risk for shoulder, hip, and patellar dislocations (see Chapter 31, Strains, Sprains, and Dislocations), pes planus (see Chapter 52, Flatfoot), and atlantoaxial instability (AAI) or laxity at C1-C2 (see Chapter 17, Atlantoaxial Rotatory Subluxation or Fixation).

• Slipped capital femoral epiphysis (see Chapter 20)

— Although treatment indications are the same, a higher complication rate is observed in patients with Down syndrome.

• Scoliosis (see Chapter 11, Idiopathic Scoliosis and Congenital Scoliosis)

• Arthropathy of Down syndrome

—

Only gold members can continue reading. Log In or Register to continue