Aneuploidy is the deletion or addition of one or a few chromosome from the original genomes e.g., (i) Monosomy is ( 2n−2 ) e.g.. Turner's syndrome. (ii) Nullisomy is ( 2n−2 ). (iii) Trisomy is ( 2n+2 ) e.g., Klinefelter's syndrome. (iv) Tetrasomy ( 2n+2 ).