Q90-Q99: Chromosomal abnormalities, not elsewhere classified

Q93: Monosomies and deletions from the autosomes, not elsewhere classified

Monosomies and deletions from the autosomes are a group of genetic conditions, which are marked by the absence or abnormality of one of the chromosomes in an individual's cells. Chromosomes are structures that hold genes, the basic units of heredity. Autosomal refers to chromosomes that are not sex chromosomes. Monosomy means that a person has one copy instead of the usual two copies of a particular chromosome in their cells, whereas deletion refers to the loss of some genetic material from the chromosome. These changes can lead to developmental problems or health issues, as essential genetic information is missing or altered. The exact symptoms can differ widely and depend on the particular chromosome that is affected. The majority of these conditions are not inherited but are caused by random errors in cell division. The progression of these conditions can vary and affects many bodily systems, all generally related to the body's growth and development.