Aneuploidy  is  gain or loss of one or
   more chromosomes, but not a complete set.
<LI> Monosomy is loss of a single chromosome from a diploid genome.
<LI> Trisomy is gain of one chromosome in a diploid genome.

   Euploidy is possession of multiples of the haploid set of chromosomes.

   Polyploidy is possession of more than two sets: triploid is three sets
   and tetraploid is four sets.