Definitions for "Trisomy"
The presence of three copies of a chromosome in an otherwise diploid cell.
a diploid organism with 3 complete sets of chromosomes.
An abnormality in chromosomal development. Chromosomes are the structures within a cell that carry its genetic information. They are organized in pairs. Humans have 23 pairs of chromosomes. In a trisomy syndrome, an extra chromosome is present so that the individual has three of a particular chromosome instead of the normal pair. An extra chromosome 18 (trisomy 18) causes mental retardation.