Aneuploidy is a genetic condition where an individual has an abnormal number of chromosomes. Instead of the typical 46 chromosomes in humans, aneuploid cells may have one or more extra chromosomes or may be missing chromosomes. This can lead to various health issues and developmental disorders. Common examples of aneuploidy include Down syndrome, which is caused by an extra copy of chromosome 21, and Turner syndrome, which occurs when a female has only one X chromosome. Aneuploidy can arise during cell division, particularly during meiosis, when gametes are formed.