What is the term for missing chromosomes?

Monosomy refers to the condition in which an individual has only one copy of a particular chromosome instead of the normal two. This results in a total of 45 chromosomes instead of the typical 46 in humans. The missing chromosome can significantly affect an organism’s development and can lead to various health complications. A well-known example of monosomy is Turner syndrome, where there is a missing sex chromosome (X0).

Understanding why this term is distinct is crucial. Trisomy, for instance, is the opposite condition where there is an extra chromosome, resulting in three copies instead of the usual two (like in Down syndrome, which involves an additional chromosome 21). Aneuploidy encompasses both monosomy and trisomy as it refers to any abnormal number of chromosomes, either missing or extra. Polyploidy indicates the presence of more than two complete sets of chromosomes, a condition that is more commonly seen in plants than in animals. Each of these different terms outlines a specific chromosomal alteration, making monosomy the precise term for the condition where chromosomes are missing.