translocation Down syndrome


A condition in which, as a result of translocation of a large segment of chromosome 21 to another chromosome, an individual has virtually the genetic equivalent of three chromosomes 21 and thus has the phenotype of Down syndrome but with the normal number of chromosomes.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.