Chronic Granulomatous disorder
Chronic granulomatous disorder (CGD) is rare genetic condition that prevents the immune system working properly to fight off bacterial and fungal infections. People with CGD carry a gene, which means that white blood cells, known as neutrophils, do not function correctly. When these neutrophils encounter bacteria and fungi in the blood, they engulf (or ‘eat’) them and attack them with chemicals such as hydrogen peroxide and superoxide – similar to bleach. This process is not effective in people with CGD, therefore, people with CGD are more susceptible to fungal and bacterial infections.
Last updated June 2017 by Professor W. Qasim, Consultant in Immunology at the Great Ormond Street Institute of Child Health, London, UK.
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Affected individuals are susceptible to serious bacterial and fungal infection. Pneumonia (inflammation of the lung tissue affecting one or both sides of the chest) can be one of the most common symptoms in addition to infections of the skin, lungs, gastrointestinal tract, lymph nodes, liver, and spleen. Another common symptom of CGD is the development of granulomas (nodules of inflammatory tissue) in the skin, gastrointestinal tract, and urinary tract. At diagnosis, some people may have symptoms related to these granulomas. Bowel problems can be also be common in those with CGD. Those affected are able to fight off viral infections as normal.
CGD is caused by a genetic mutation (change) in the instructions for neutrophils cells. Four proteins – Gp91-phox, p22-phox, p47-phox and p67-phox – form part of the enzyme NADPH oxidase, responsible for the production of bleach-like chemicals that enable neutrophils to kill bacterial or fungal invaders. There are four different types of CGD and each of these types is determined by where the genetic mutation lies.
Three-quarters of people are diagnosed during the first five years of life. CGD can be diagnosed by a simple blood test. This test, called the nitroblue tetrazolium dye reduction test, is based on the ability of patient’s phagoctye cells to produce an oxygen burst. It is this oxygen burst that is important for neutralising bacteria and fungi within cells. Increasingly this test is slowly being replaced by a more sophisticated method called dihydrorhodamine (DHR) test.
If CGD is suspected, it is important that referral is made to a specialist centre and diagnostic tests carried out in a laboratory that is familiar with doing these tests on a regular basis.
Treatment is by daily use of antibiotics and antifungal drugs to prevent infection, other medicines may be given to deal with problems associated with CGD such as inflammation. It is extremely important to contact a doctor if an infection is suspected so that prompt treatment can be given.
Blood or bone marrow stem cell transplantation is the only treatment at the present time which can cure CGD. This involves clearing out a patient’s own bone marrow with chemotherapy and replacing it with bone marrow with from a healthy tissue-matched donor. Donors are usually unaffected siblings or volunteer matched unrelated donors (MUDs) from organisations such as the Nolan Registry. Transplant can be a difficult procedure and carries significant risks, but outcomes have improved notably over recent years, even when donors are mismatched or half-matched (Haplos). A small number of children have also been treated using umbilical cord blood stem cell collections. These procedures are only performed at specialist bone marrow transplant centres.
Gene therapy aims to add a corrected copy of the defective gene to a patient’s own bone marrow or blood stem cells. Only a small number of patients have been treated so far and whilst some have experienced benefits there could be side effects and clinical trials have started to test these approaches. New techniques called ‘gene-editing’ are also in development and aim to improve the safety and success of these treatments in the future.
The condition can be inherited in an X-linked manner (only boys can be affected) and in an autosomal recessive manner (boys and girls may be affected). Affected families should be referred to a regional genetics centre for information and advice.
This is possible where the mother is a known carrier (has the gene defect but no symptoms) of CGD.
Chronic Granulomatous Disorder Society
The Society is a Registered Charity in England and Wales No. 1143049. It offers information and support for individuals and families affected by chronic granulomatous disorder (CGD). The Society offers paediatric and adult nursing services, and financial assistance to patients affected by CGD and their families.
Group details last updated June 2017.