Visual communication aid: Chromosome duplications and microduplications
This communication aid has been produced to complement discussions about preimplantation genetic testing (PGT-M and PGT-SR) during consultations with patients.
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There is one communication aid available to view and download (.pdf):
Double-sided printing in colour is recommended (but not required). All content is also included below in an accessible format.
More information about these and other VCAs is available in this article.
Chromosomes explained
We all have over 20,000 genes, which provide instructions for how our body works. Our genes are packaged into structures called chromosomes.
People usually have 23 pairs of chromosomes: 22 pairs of autosomes and one pair of sex chromosomes (XX or XY). One chromosome from each of each pair is inherited from each parent. Our sex chromosomes are called X or Y, and usually determine sex assigned at birth.
Chromosomes have a short arm, known as the p arm, and a long arm, known as the q arm. The p arm and q arm are joined together by a centromere.
You can learn more about the basics of our genome in this VCA: Genes, chromosomes and DNA.
What are chromosome duplications and microduplications?
A duplication is a gain of DNA, where a section of chromosome has an extra copy. Duplications can be large or small. Large duplications can be seen under a microscope. Duplications that are too small to be seen under a microscope are known as microduplications.
A duplication may include a part of a gene, a whole gene or multiple genes.
Duplications are usually described based on the chromosome affected and the location of the duplication on the chromosome.
Some duplications may not have any effect on a person’s health. Some duplications may cause a genetic condition.
Figure 1: Example of a chromosome duplication
(View larger size)
Key terms
- Genome: The complete set of genetic information found inside a cell.
- Chromosome: Packages of DNA that are found in our cells.
- Autosome: A chromosome that is not a sex chromosome
(named 1–22). - Sex chromosome: A chromosome containing genes that determine the sex a person is born as (named X or Y).