When a change in the chromosome number does not involve entire sets of chromosome and restrict to only a few of chromosome, the situation is called aneuploidy. Aneuploidy may be of following types
(a) Monosomic (2n−1)
(b) Trisomic (2n+1)
(c) Nullisomic (2n−2)
(d) Tetrasomic (2n+2)
(e) Double momosomic (2n−1−1)
(f) Double trisomic (2n+1+1)