NCIt definition : A chromosomal abnormality in which there is an addition or loss of chromosomes within
a set (e.g., 23 22 or 23 24).;
Alternative definition : NCI-GLOSS: The occurrence of one or more extra or missing chromosomes leading to an
unbalanced chromosome complement, or any chromosome number that is not an exact multiple
of the haploid number (which is 46).;