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Chronic granulomatous disease
CGD leads to recurrent, severe infections and inflammatory complications, primarily affecting the lungs, skin, and gastrointestinal tract. It typically presents in childhood and requires lifelong management to prevent serious health problems.
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Overview
Chronic Granulomatous Disease (CGD) is a primary immunodeficiency disorder affecting a specific part of the immune system. In CGD, immune cells called phagocytes - such as neutrophils and macrophages - are unable to produce a vital burst of reactive oxygen species, often referred to as the 'respiratory burst' [PMID:33675038]. This respiratory burst is crucial for killing certain types of bacteria and fungi that have been engulfed by these immune cells. Without this defence mechanism, individuals with CGD are highly susceptible to severe, persistent, and recurrent infections.
CGD is a rare condition, estimated to affect approximately 1 in 200,000 to 250,000 people in the general population. While CGD is typically diagnosed in childhood, some individuals may experience milder symptoms or a later diagnosis, particularly with specific genetic forms. Lifelong management is generally required to reduce the risk of serious complications.
Symptoms & clinical features
The symptoms of Chronic Granulomatous Disease arise from the body's inability to fight off specific infections and from excessive inflammation. Common sites for infections include the lungs, skin, lymph nodes, liver, and gastrointestinal tract. Persistent pneumonia, skin abscesses, and enlarged lymph nodes are frequently observed [PMID:28795552].
Beyond infections, individuals with CGD can also develop inflammatory conditions due to the immune system's dysregulation. This can manifest as granulomas - clusters of immune cells that form at sites of infection or inflammation - which can obstruct organs, particularly in the gastrointestinal or genitourinary systems. Other inflammatory issues may include inflammatory bowel disease-like symptoms, liver inflammation, and autoimmune-like conditions.
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Affected organs
CGD can affect various organ systems throughout the body. The lungs are frequently involved, with recurrent bacterial or fungal pneumonias being a common issue. The skin can develop abscesses, boils, and unusual rashes. Lymph nodes, crucial components of the immune system, often become swollen and infected.
The gastrointestinal tract is another commonly affected area, where granulomas can lead to blockages or symptoms resembling inflammatory bowel disease. The liver and spleen can also be sites of infection or inflammation, leading to abscesses or enlargement. Bone infections (osteomyelitis) are also reported in some individuals with CGD [PMID:30554160].
Risks & severity
The severity of Chronic Granulomatous Disease can vary among individuals, depending on the specific genetic change and the extent to which the immune system's function is impaired. Without appropriate treatment, individuals with CGD face a significant risk of severe, life-threatening infections, particularly from common environmental bacteria and fungi that typically pose little threat to healthy individuals.
Complications such as organ damage due to chronic inflammation or severe infections are also a concern. Early diagnosis and consistent adherence to preventative treatments are crucial to improving long-term health outcomes and reducing the impact of the condition. Lifelong vigilance and regular medical follow-up are typically necessary.
Genetic causes
Chronic Granulomatous Disease is caused by changes (pathogenic variants) in genes that are essential for the proper functioning of the NADPH oxidase enzyme complex. This enzyme complex is vital for phagocytic cells to produce reactive oxygen species, which are part of their mechanism to kill engulfed pathogens.
Several genes are known to be associated with CGD. These include *CYBA*, *CYBB*, *NCF1*, and *NCF2*. The *CYBA* gene provides instructions for making the p22-phox protein, while the *CYBB* gene codes for the gp91-phox protein. Both of these proteins are crucial subunits of the cytochrome b-245 component of the NADPH oxidase enzyme. The *NCF1* and *NCF2* genes produce p47-phox and p67-phox proteins, respectively, which are also essential for the NADPH oxidase complex to function correctly. Pathogenic variants in any of these genes disrupt the enzyme's ability to generate the necessary reactive oxygen species, leading to the immune dysfunction seen in CGD.
- CYBA cytochrome b-245 alpha chainThe CYBA gene provides instructions for the cytochrome b-245 alpha chain protein, a crucial component of the NADPH oxidase enzyme complex involved in immune function.
- CYBB cytochrome b-245 beta chainCYBB encodes the beta chain of an enzyme complex essential for generating antimicrobial molecules in immune cells, with variants causing chronic granulomatous disease.
- NCF1 neutrophil cytosolic factor 1The NCF1 gene provides instructions for a protein critical to the immune system's defence against pathogens, particularly bacteria and fungi.
- NCF2 neutrophil cytosolic factor 2The NCF2 gene provides instructions for producing the p67-phox protein, a key component of the NADPH oxidase enzyme complex vital for immune responses, particularly in fighting infections.
Inheritance pattern
Chronic Granulomatous Disease typically follows an autosomal recessive pattern of inheritance. This means that an individual must inherit two altered copies of the same gene - one from each parent - to develop the condition. Parents who each carry one altered copy of the gene are generally healthy and are known as carriers.
When both parents are carriers of an autosomal recessive condition, there is a 1 in 4 (25%) chance with each pregnancy that their child will inherit two altered gene copies and develop CGD. There is also a 1 in 2 (50%) chance that their child will be a carrier, and a 1 in 4 (25%) chance that their child will inherit two unaffected gene copies and not be a carrier.
When both parents are carriers, each child has a 25% chance of being affected, 50% of being a carrier, and 25% of being unaffected.
Diagnosis & testing
Diagnosing Chronic Granulomatous Disease often begins with a suspicion based on recurrent, severe infections or unusual inflammatory reactions. The definitive diagnosis relies on specific laboratory tests that assess the function of neutrophils, the most abundant type of phagocyte.
The dihydrorhodamine (DHR) flow cytometry test is the most common and reliable method. This test measures the production of reactive oxygen species by neutrophils and can identify if this process is impaired. Genetic testing, typically involving analysis of the *CYBA*, *CYBB*, *NCF1*, or *NCF2* genes, is then used to confirm the diagnosis and identify the specific genetic cause. In the UK, genetic testing for suspected primary immunodeficiencies falls under the NHS National Genomic Test Directory (e.g., R-codes R123, R124, R128). Referrals for genetic testing are typically made by immunology or paediatric specialists to clinical genetics services.
Management & lifestyle
Management for Chronic Granulomatous Disease focuses on preventing infections, treating active infections aggressively, and managing inflammatory complications. Prophylactic antibiotics and antifungal medications are commonly prescribed to reduce the risk of infections. Interferon-gamma therapy may also be used in some cases to enhance immune function.
Care is typically managed by a team of specialists, including immunologists, infectious disease specialists, and gastroenterologists. Regular monitoring for signs of infection and inflammation is essential. In severe cases, or when other treatments are not sufficient, a stem cell transplant might be considered as a potential curative option. Lifestyle adjustments, such as avoiding certain mould-prone environments (e.g., decaying leaves, compost), are also often recommended to minimise pathogen exposure.
UK care pathway
In the UK, suspected cases of primary immunodeficiencies like Chronic Granulomatous Disease are typically referred to specialist immunology or paediatric immunology teams within the NHS. Genetic testing is available through the NHS Genomic Medicine Service, guided by the National Genomic Test Directory R-codes (e.g., R123 for Severe Primary Immunodeficiency). Following a confirmed diagnosis, individuals and families are often referred to clinical genetics services for genetic counselling. This provides comprehensive information about the condition, its inheritance pattern, and implications for family members.
Frequently asked questions
What is the life expectancy for someone with CGD?
With early diagnosis and consistent, appropriate medical management, individuals with CGD can often live well into adulthood. Advances in treatments, particularly prophylactic antibiotics and antifungals, have significantly improved the prognosis for many with the condition.
Can CGD be cured?
Currently, the only known curative treatment for CGD is a stem cell transplant (also known as bone marrow transplant). However, this procedure carries significant risks and is considered in specific situations, weighing the potential benefits against the risks involved.
Are there specific infections I should be particularly worried about with CGD?
Individuals with CGD generally have difficulty fighting off certain types of bacteria (e.g., Staphylococcus aureus, Serratia marcescens) and fungi (e.g., Aspergillus species). It is important to discuss specific infection risks and preventative measures with your medical team.
How does CGD affect daily life?
Living with CGD often involves taking daily preventative medications and being vigilant for signs of infection. Regular medical appointments are typically necessary. While some activities might need careful consideration (e.g., avoiding mouldy environments), many individuals with CGD can lead full and active lives with proper management.
What support is available for families affected by CGD in the UK?
Families in the UK can access support from various organisations such as Immunodeficiency UK, which provides resources and connects patients with primary immunodeficiencies. Clinical genetics services and genetic counsellors can also offer guidance and support after diagnosis.
References
- Roos D. Chronic Granulomatous Disease. Methods in molecular biology (Clifton, N.J.). 2019. PMID: 31172494
- Roos D. Chronic granulomatous disease. British medical bulletin. 2016. PMID: 26983962
- Holland SM. Chronic granulomatous disease. Hematology/oncology clinics of North America. 2013. PMID: 23351990
- Goldblatt D, Thrasher AJ. Chronic granulomatous disease. Clinical and experimental immunology. 2000. PMID: 11012609
- Blattner RJ. Chronic granulomatous disease. The Journal of pediatrics. 1969. PMID: 4303071
- Cytochrome B and chronic granulomatous disease. Lancet (London, England). 1979. PMID: 86784
- Thrasher AJ, Keep NH, Wientjes F. Chronic granulomatous disease. Biochimica et biophysica acta. 1994. PMID: 7918677
- Johnston RB, Newman SL. Chronic granulomatous disease. Pediatric clinics of North America. 1977. PMID: 323805