Conditions of a karyotype 2n +1, 2n –1 and 2n + 2, 2n – 2 are called:

Conditions of a karyotype 2n +1, 2n –1 and 2n + 2, 2n – 2 are called Aneuploidy. Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s), called aneuploidy.

2n-2 is nullisomy and 2n+2 is tetrasomy.

A trisomic cell has one extra chromosome with karyotype as 2n+1, for example trisomy 21 (Down’s syndrome) and a monosomic cell has one missing chromosome with karyotype 2n-1, for example Turner’s syndrome (monosomy XO).