How is CGD diagnosed?
Doctors usually diagnose CGD in childhood.
If a child has a family history of CGD, doctors will use a blood test to check for the condition. Children who have symptoms may also be tested. These may include severe or recurrent bacterial or fungal infections, or enlarged lymph nodes.
Most people will have symptoms by the time they are three years old. Doctors diagnose 95 per cent of people affected by the age of five. However, some aren’t diagnosed until they’re adults, despite showing symptoms earlier.
Testing for CGD
The DHR (dihydrorhodamine) (flow cytometry test) and NBT (nitroblue tetrazolium) tests are used to diagnose CGD. Both work in a similar way. They check if someone's blood cells are producing the enzyme NADPH oxidase, which plays a vital role in the way white blood cells fight infection
If blood cells are fighting infection as they should do, the DHR test will change the fluorescence of dihydrorhodamine. This can be detected by a machine called a flow cytometer.
In the NBT test, the colour of the cell being tested will change and this can be detected through a microscope. Both are good tests but skill is needed to interpret results, so they need to be carried out by experts.
Is there more testing after diagnosis?
Once CGD is diagnosed, doctors may need to do further x-rays, blood and urine tests, depending on the person’s symptoms. The faulty gene can also be defined by using a genetic test that analyses a person’s DNA and looks for changes in the genes coding for the enzyme NADPH oxidase.
They will also do baseline blood tests when the person is healthy, so they can compare results if they get ill and find out what might be causing problems.
It’s vital that people with CGD have regular blood tests so any problems can be found and treated early.
What are some common symptoms of CGD?
People with CGD often have bacterial infections including Staphylococcus aureus, Pseudomonas, Salmonella, Klebsiella, Actinomyces, Streptococcus, Norcardia and Serratia.
Fungal infections are also common, including Aspergillus fumigatus and Aspergillus nidulans.
Signs of these infections, and other symptoms of CGD, include:
- Failing to gain weight or grow normally as an infant
• Sores with pus or rashes anywhere on the body, including on the scalp and around and inside the nose
• Abscesses or boils
• Ulcer-like sores
• Sores around the bottom
• Difficulty or pain when urinating
• Warm, tender or swollen areas
• Swollen lymph nodes – hard lumps in the back of the ears or the groin area
• Persistent diarrhoea
• Lots of infections that might disappear with antibiotics, but keep coming back or where antibiotics have little effect
• Two or more pneumonias in one year
The liver, gastrointestinal tract and urogenital tract are particularly susceptible to inflammation in CGD patients. Infections are also common in the lungs, lymph nodes, skin, liver, nostrils mouth and sometimes bones (osteomyelitis).
Reviewed by the Medical Advisory Panel, February 2020
Read more about the different types of CGD.
Read more about how CGD is inherited.
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