A clinical syndrome due to trisomy 21 (i.e. three copies of chromosome 21)

I. Clinical Features-Not always apparent @ birth; highly variable presentation

  1. Congenital cardiac defects (occur in 50%; e.g. ventricular septal defect)
  2. Hearing loss (both sensorineural and due to serous otitis media-50-70% incidence of the latter from 3-5yo)
  3. Ophthalmologic disorders ("Brushfield" spots-white spots on iris, strabismus, cataracts, nytagmus; 50% have refractive error by 5yo)
  4. Congenital hypothyroidism (occurs in about 1%)
  5. Neonatal leukemia (occurs in < 1%, though a "leukemoid reaction" is present in > 10% of children with Down Syndrome)
  6. Gastrointestinal abnormalities (e.g. duodenal atresia, which occurs in 12%, usually presenting < 3yo)
  7. Joint laxity including atlantoaxial instability (10-20% prevalence; clinically significant in 1-2%)
  8. Obstructive sleep apnea (occurs in 50-75% of individuals with Down Syndrome)
  9. Celiac disease
  10. Characteristic facies with microgenia (abnormally small chin), oblique eye fissues with epicanthic skin folds, flat nasal bridge, and protruding tongue due large size and to small oral cavity
  11. Single palmar fold
  12. Delayed stature (though bone age is not as delayed)

II. Diagnosis and workup

  1. Re: prenatal screening for Down Syndrome in pregnant women, see under Screening for Congenital Abnormalities
    1. If screening suggests, consider intrauterine echocardiography & ultrasound to identify cardiac and GI abnormalities
  2. Typical physical appearance of infant
  3. Confirmed by karyotype analysis
  4. If Down Syndrome is confirmed, consider the following in the neonatal period:
    1. Echocardiography and pediatric cardiology consultation (cardiac defects may be clinically inapparent initially)
    2. Hearing screening by 3mos (e.g. by brainstem auditory evoked response or otoacoustic emission)
    3. Ophthalmologic evaluation by 6mos
    4. Screening for congenital hypothyroidism (TSH) and leukemia (CBC)

III. Ongoing screening

  1. Assess at each well-child visit for potential clinical features noted above
  2. If can't visualize tympanic membranes (frequently the case due to stenosis of external auditory meatii), consider otolaryngology referral to look for serous otitis media
  3. Repeat thyroid testing at 6mos and 12mos then Q1y
  4. Repeat CBC Q1y
  5. Consider "behavioral" audiogram at 1yo (then Q6mos through 5yo if tympanic membranes cannot be fully visualized)
  6. Ophthalmologic evaluation Q2y
  7. Screen for atlantoaxial instability with lateral cervical spine radiographs (with neutral, flexion and extension views) at 3-5yo (definitely prior to sports participation)
  8. Symptom screen for obstructive sleep apnea at each WCC
  9. Consider using Down Syndrome-specific growth charts since growth patterns in children with Down Syndrome tend to be different from those in other children
  10. Consider screening for celiac disease if symptoms are present

(Sources include Core Content Review of Family Medicine, 2012)