Chromosomal abnormalities occur when there are errors in chromosome number or structure during cell division. Some abnormalities are caused by nondisjunction, where chromosomes do not separate properly during meiosis. This can result in having too many or too few chromosomes and cause disorders like Down syndrome, a condition caused by trisomy 21 where a third copy of chromosome 21 is present. Other abnormalities involve deletions, duplications, inversions or translocations of genetic material between chromosomes.

1. Chromosomal Abnormalities

8. Alteration of chromosome number

12. Trisomy 21