|Karyotype||A picture of an individual’s chromosomes in which the chromosomes are paired and arranged in order of decreasing size.|
|Monosomy||The lack of one of a pair of chromosomes. A common monosomy is X chromosome monosomy, known in humans as Turner syndrome and denoted as 45, X.|
|Trisomy||Condition of having three chromosomes of a particular type. A common trisomy in humans is Down syndrome, or trisomy A male with trisomy 21 is denoted as 47, XY, 21+.|
Failure of chromosome pairs to separate during meiosis I or meiosis II.