CGD – The basics

CGD is a disorder that prevents the immune system fighting off certain infections.  People with CGD carry a faulty immune system gene, which means that white blood cells, called phagocytes, don’t work properly.  As a result, CGD-affected people tend to get frequent bacterial and fungal infections, and need to take daily medication to stay healthy. However, many of the health complications seen in people with CGD are due to chronic inflammation rather than infection.

Problems can arise and lead to serious illnesses and prolonged periods in hospital.  The condition is thought to affect around eight people in a million.

People with CGD can’t fight bacterial or fungal infections effectively.

They have a faulty immune system gene, which means that some of their white blood cells, called neutrophils, don’t work properly.

In a healthy person, neutrophils kill fungi and bacteria. When they encounter them in the blood, they engulf (or ‘eat’) and attack them with chemicals known as enzymes that kill the microbes.

People with CGD can’t produce these attacking chemicals, because genetic mutations mean they are missing a vital protein in an enzyme called NADPH oxidase. This makes them more susceptible to fungal and bacterial infections. Sometimes, these are serious or even life-threatening.

Infections can include abscesses, enlarged lymph glands, unusual pneumonias or bone infections. Inflammatory problems can be severe and include inflammation of the bowel (colitis), lung, bladder (cystitis) and gums (gingivitis).  Sometimes problems are caused by granulomas. These are nodules of immune cells that form tight ball-like structures that can cause obstruction in body tissues.

Skin conditions including acne are also seen commonly.

CGD is an inherited disorder which means that it is passed from parents to their children.  One type of CGD is ‘X-linked’ (sex-linked) and the other four are ‘autosomal recessive’.

An X-linked disorder means the CGD-affected gene comes from the mother and that her daughters may be carriers and for every pregnancy there is a 50 per cent chance that her sons will be affected by the condition. An autosomal recessive disorder is when a condition or trait develops because two copies of an abnormal gene – one from each parent – are present.

It’s a rare condition. In the UK, CGD affects about eight people in a million. According to estimates, in the US and Europe, nearly 6,000 people have CGD.

People with CGD need to take medication all the time to prevent infections.

Even then, they can develop serious problems, which lead to life-threatening illnesses and long spells in hospital.

As well as medication, doctors have been having increasing success in treating CGD with bone marrow transplants. Marrow has come from both relatives and unrelated donors.

However, there is no one treatment or cure for all people with CGD. And a bone marrow transplant isn’t possible for everyone.

Exciting gene replacement therapy trials are underway at the moment, and there’s hope this may find a cure. However, more work is needed before it can become a regular treatment option. Gene therapy is a relatively new branch of medicine. Research is ongoing to improve the outcomes of gene therapy for CGD with the intention that it offers an alternative for permanent cure.

Remember, research into CGD doesn’t just help people with this rare genetic condition. Every breakthrough scientists make could potentially help millions as any advances could shed light on how other genetic disorders work.

Reviewed by the Medical Advisory Panel, February 2020