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  • Down syndrome

  • Trisomy 21


  • 758.0 Down syndrome


  • Q90.0 Trisomy 21, nonmosaicism (meiotic nondisjunction)

  • Q90.1 Trisomy 21, mosaicism (mitotic nondisjunction)

  • Q90.2 Trisomy 21, translocation

  • Q90.9 Down syndrome, unspecified


  • 4C: Impaired Motor Performance1


A 6-month-old infant is referred to physical therapy from an early intervention program with a diagnosis of Down syndrome. The parents report the infant was diagnosed in utero and was born at full term; otherwise, the pregnancy and delivery were uneventful. Upon examination, the infant is hypotonic and not yet rolling. In prone, the infant can achieve prone on elbows but not yet prone on extended arms. In supine, the infant exhibits decreased activity when reaching against gravity or kicking the legs. There is a mild head lag when pulled into sitting and mild trunk flexion when supported in sitting. The infant does not take weight on the legs when held in supported standing. As a result, direct physical therapy services are recommended.



  • Genetic disorder characterized by cognitive impairment and stereotypical physical features

    • Hypotonia

    • Short stature

    • Simian crease

    • Upward-slanting eyes

    • Protruding tongue

Essentials of Diagnosis

  • Abnormality of chromosome 21 with three arms rather than two, or translocation

  • Can be detected in the early second trimester

FIGURE 238-1

Down syndrome. (From Fuster V, Walsh RA, Harrington RA. Hurst’s The Heart. 12th ed. Copyright © The McGraw-Hill Companies, Inc. All rights reserved.)

General Considerations

  • Associated disorders

    • 50% have heart defects.

    • 52% have scoliosis.2

    • 60% to 80% have hearing deficits.2

    • 90% have umbilical hernia.2

    • 15% have atlantoaxial instability.3

    • Leukemia.

    • Hip subluxation.

    • Congenital or adult-onset cataracts or other visual deficits.


  • Marked rise in risk in mother aged 35 years and over

  • At maternal age 45, risk is 1:40

  • 1 per 700 births4



  • Facial feature

    • Flat occiput

    • Large tongue

    • Protruding tongue

  • Hypotonia

  • Single palmar crease

  • Hypothyroidism

  • Celiac disease

  • Ligamentous laxity: Atlanto-axial instability

  • Congenital heart disease

  • Pes planus

  • Obesity

  • Delays in

    • Gross motor skills

    • Fine motor skills

    • Oral motor skills

    • Perceptual motor skills

    • Social-emotional skills

    • Speech and language skills

Possible Contributing Causes

  • Gene deletions

  • Chromosome translocation

  • Chance mutation

  • Angelman syndrome

Functional Implications

  • Poor head and trunk control as infant

  • Refusal to bear weight on feet

  • Learn to sit independently between 12 to15 months of age instead of ...

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