Aneuploidy is a condition in which the chromosomes do not separate properly between daughter cells during meiosis. The chromosome number for an individual organism differs from the standard chromosome number of a particular species, often causing genetic disorders such as human birth defects, notes Wikipedia.
Most cells in the human body contain 23 pairs of chromosomes, with one copy of each pair inherited from the mother and the other copy inherited from the father. The first 22 pairs of chromosomes are autosomes and the last pair is sex chromosomes. According to "An Introduction to Genetic Analysis," aneuploidy may result in extra autosomal genetic disorders, sex chromosome disorders or termination of the developing fetus.