Down syndrome
Down syndrome; Characterized by variable degrees of mental retardation, characteristic facial features, some retardation of growth and development, and an increased incidence of heart defects, leukemia, and other abnormalities; caused by the duplication of all or part of chromosome 21 (trisomy 21).
© 2005 by W. H. Freeman and Company. All rights reserved. Pierce, B. Genetics: A conceptual approach. 2nd Edition.
