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.
(a question on epidemiology would also include recurrence risks according to the karyotypic findings: see paragraph on 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.
Huret JL, Sinet PM
Atlas of Genetics and Cytogenetics in Oncology and Haematology 2000-08-01
Online version: http://atlasgeneticsoncology.org/teaching/30085/trisomy-21