Difference between revisions of "Down syndrome"

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'''Down syndrome''', is a common genetic abnormality.  It may also be called '''Trisomy 21'''; however, technically this may not be completely correct in all cases.
'''Down syndrome''', abbreviated '''DS''', is a common genetic abnormality.  It may also be called '''Trisomy 21'''; however, technically this may not be completely correct in all cases.


==Genetics==
==Genetics==

Revision as of 22:30, 13 June 2012

Down syndrome, abbreviated DS, is a common genetic abnormality. It may also be called Trisomy 21; however, technically this may not be completely correct in all cases.

Genetics

Down syndrome can be the result of three different defects:[1]

Defect Percent of DS Notes
Extra chromosome 21 (trisomy 21) ~95% defect seen more often with increasing maternal age
Robertsonian translocation ~4% part of chromosome 21 attaches to chromosome 22 or 14; one parent is a carrier -- recurrence virtually 100%; no age dependence
Mosaicism ~1% some cells have a triple dose of chromosome 21 while others have a normal number of chromosome 21; no age dependence

Characteristics

Mnemonic CHILD HAS PROBLEM:[2]

  1. Congenital heart disease / Cataracts.
  2. Hypothyroidism / Hypotonia.
  3. Incurved 5th digit (clinodactyly)[3] / Increased gap between 1st and 2nd toe.
  4. Leukemia risk x2 / Lung problem.
  5. Duodenal atresia / Delayed development.
  6. Hirschsprung disease / Hearing loss.
  7. Alzheimer disease / Alantoaxial instability.
  8. Short neck / Squint.
  9. Palmar crease / Protruding tongue.
  10. Round face / Rolling eye (nystagmus).
  11. Occiput flat / Oblique eye fissure.
  12. Brushfield spots / Brachycephaly.
  13. Low nasal bridge / Language problems.
  14. Epicanthic fold / Ears folded.
  15. Mental retardation / Myoclonus.

Notes:

  • Brushfield spots = white/grey spots in the iris (the "colour part" of the eye).

Simplified

Simplified version of mnemonic CHILD HAS PROBLEM:

  1. Congenital heart disease.
  2. Hypothyroidism.
  3. Incurved 5th digit (clinodactyly) / Increased gap between 1st and 2nd toe.
  4. Leukemia risk x2.
  5. Duodenal atresia.
  6. Hirschsprung disease.
  7. Alzheimer disease / Alantoaxial instability.
  8. Short neck.
  9. Palmar crease / Protruding tongue.
  10. Round face.
  11. Occiput flat / Oblique eye fissure.
  12. Brushfield spots / Brachycephaly.
  13. Low nasal bridge.
  14. Epicanthic fold / Ears folded.
  15. Mental retardation.

See also

References

  1. ↑ Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 99. ISBN 978-1416054542.
  2. ↑ URL: http://www.valuemd.com/genetics.php. Accessed on: 29 May 2011.
  3. ↑ URL: http://www.handresearch.com/diagnostics/simian-line-down-syndrome.htm. Accessed on: 29 May 2011.

External links

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