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Trisomy 21

  • The most frequent viable chromosome disease.
  • Like other inborn autosomal chromosome diseases, associates dysmorphia + psycho-motor delay, and possible visceral malformations (found in more than 1/3 of cases); a medico-pedagogic care and follow up must be undertaken.






    I. EPIDEMIOLOGY


    (a question on epidemiology would also include recurrence risks according to the karyotypic findings: see paragraph on the karyotype).
  • 1,5 /1 000 births.

  • Sex ratio: 3 males/2 females.

  • Increased median maternal age (34 years).






    II. CLINICAL EXAMINATION


    1 - Dysmorphic syndrome associating (to various extend):



    2 - Psycho-motor delay (constant):



    3 - Dermatoglyphics:



    This association of signs implicates that visceral malformations have to be searched for, as they can burden the vital prognosis and impose that emergency treatments be started.

    4 - Malformations (45% of cases):


    5 - Other:



    III. DIAGNOSIS: THE KARYOTYPE


    proves the diagnosis, allows/implicates a genetic counseling:
    recurrence risk is about 1 % if the anomaly is de novo, more if one of the parents is a translocation carrier.

  • Free and homogeneous trisomy 21 (92,5 % of cases):

  • Free trisomy 21 in mosaic (2,5 % of cases):


  • Trisomy 21 due to translocation:

    IV. EVOLUTION




    V. PROGNOSIS





    VI. TREATMENTS




    Contributor(s)

    Written08-2000Jean-Loup Huret, Pierre-Marie Sinet
    CNRS UMR 8602, Faculté de Médecine Necker Enfants Malades, Paris, Franc

    Citation

    This paper should be referenced as such :
    Huret JL, Sinet PM . Trisomy . Atlas Genet Cytogenet Oncol Haematol. August 2000 .
    URL : http://AtlasGeneticsOncology.org/Educ/PolyTri21Eng.html

    The various updated versions of this paper are referenced and archived by INIST as such :

    © Atlas of Genetics and Cytogenetics in Oncology and Haematology
    indexed on : Sat Feb 1 17:16:14 CET 2014

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