Definition: A numerical or structural change in a chromosome (the package of DNA inside the nucleus of a cell). A numerical chromosomal abnormality is having more or fewer than the normal 46 chromosomes in each cell. A structural chromosomal abnormality occurs when a portion of the chromosome is duplicated or deleted, or the order of genes on the chromosome is changed.
Source: Genetic and Rare Diseases (GARD) Information Center
  • Chromosomal disorder
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