Aneuploidy- A loss or gain of one or few chromosomes from the somatic chromosome number of a species is known as aneuploidy. For example, humans have 46 chromosomes of which 44 are somatic chromosomes and two are sex chromosomes.

If an individual has only 45 chromosomes and he misses one somatic chromosome, then it is called as aneuploidy. Aneuploidy changes the chromosome number and does not involve the whole genome. Non disjunction is the case of aneuploids.