What is aneuploidy?

Aneuploidy refers to a condition in which an individual has a chromosome number that deviates from the normal diploid number by an addition or subtraction of one or more chromosomes. This means that the total count of chromosomes is not a multiple of the haploid number, which in humans is 23. Therefore, any variation from the expected count of 46 chromosomes (the normal diploid count) qualifies as aneuploidy, encompassing both conditions where there are too many (trisomy) or too few (monosomy) chromosomes.

Understanding the definition of aneuploidy is critical, especially in the context of genetic diseases and conditions that can arise from these chromosomal abnormalities. For example, Down syndrome is an example of aneuploidy resulting from an extra chromosome 21 (trisomy 21).

The other options presented describe different chromosomal conditions but do not define aneuploidy accurately. Having an excess of one chromosome specifically indicates a form of aneuploidy, but it does not encompass all forms, as aneuploidy can also include loss of chromosomes. A complete lack of chromosomes (option C) represents a state of monosomy for all chromosomes, which is not a