What is aneuploidy?

Aneuploidy is any chromosomal condition that results from having an unusual number of chromosomes in a cell, such as having either a missing (monosomy) or extra chromosome (trisomy). The most common type of aneuploidy is trisomy, which means there is an extra chromosome (e.g. trisomy 21 is Down's syndrome). A common monosomy, in which a chromosome is missing, is Turner syndrome.

The chances of having a baby with an aneuploidy increases with the maternal age of the mother (i.e. the older the mother is, the higher the risk of having a child with an aneuploidy).

Doctors that specialise in aneuploidy are clinical geneticists.

How many chromosomes do we normally have?

Humans normally have 46 chromosomes, arranged in 23 pairs, with one chromosome in each pair inherited from each parent. Aneuploidy is the occurence of an abnormal number of chromosomes, such as the addition or loss of one or more chromosomes, resulting in a number of chromosomes that is not a multiple of 23.

How does aneuploidy occur?

Aneuploidy can occur in any of the chromosomes, and can lead to a wide range of genetic disorders and health issues. 

The occurence of aneuploidy can happen due to errors in cell division particularly during meiosis (the production of the sperm and egg), or during mitosis (the creation of new cells in the body). There can be many causes of these errors within these processes, and can be related to factors such as genetics, environmental factors, and other factors.

Aneuploidy is a significant area of study within genetics and is important in the understanding of human development, genetic disorders, and certain medical conditions.

What are the most common types of aneuploidy?

The most common forms of aneuploidy include:

• Down's syndrome (Trisomy 21)
• Edwards syndrome (Trisomy 18)
• Patau's syndrome (Trisomy 13)
• Turner syndrome (Monosomy X)
• Klinefelter syndrome
• XYY syndrome
• Triple X syndrome (Trisomy X)

If you wish to book an appointment with a specialist in the different forms of aneuploidy, you can find them here.