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Types of CGD

CGD is an inherited disorder, which means that it is passed from parents to their children.

There are two types of CGD, called X-linked CGD and autosomal recessive CGD. Which type a person has depends on how it has been inherited from their parents.  The different types cause some proteins in their blood cells not to work properly.

Both types of CGD cause similar symptoms. However, sometimes symptoms can be more severe with the X-linked type.

What causes CGD?

Most cells in the body contain over 100,000 genes. They are grouped together on chromosomes, long strings of genes. Each gene contains a code that can be translated by the cell to make a protein.  The type of protein that is made decides a particular characteristic of a person such as eye colour or blood type.

Both X-linked and autosomal CGD affect the enzyme NADPH oxidase which contains four proteins called Gp91-phox, p22-phox, p47-phox and p67-phox. This enzyme is involved in the production of bleach-like chemicals that make it possible for white blood cells to kill infections in our blood.

If someone has CGD, one of these four proteins is missing or defective, due to a genetic mutation, so their bodies can’t produce the bleach-like chemicals.

In X-linked CGD, the Gp91-phox protein is affected. This is the most common type of CGD, affecting around 60 per cent of people with the condition. It only affects males.

In autosomal recessive CGD, other parts of the enzyme are affected. This type of CGD affects both males and females, and there are three sub-types:

- the p47-phox form, affecting around 30 per cent of people affected by CGD.
- p22-phox and p67-phox, affecting around 10 per cent of people with CGD.

 

More information

Read more about the basics of CGD

Read more about how CGD is diagnosed

Read more about how CGD is inherited

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