A mutation in one of five genes can cause CGD. People with CGD inherit the gene mutation from a parent. The genes normally produce proteins that form an enzyme that helps your immune system work properly. The enzyme is active in white blood cells (phagocytes) that catch and destroy fungi and bacteria to protect you from infections. The enzyme is also active in immune cells that help your body heal.
When there are mutations to one of these genes, the protective proteins are not produced, or they're produced but they don't function properly.
Some people with CGD don't have one of these gene mutations. In these cases, doctors don't know what causes the condition.