X-Linked Chronic Granulomatous Disease (X-CGD)
Description
X-Linked Chronic Granulomatous Disease (X-CGD) is a rare, inherited disorder that primarily affects the immune system. Individuals with X-CGD have a weakened immune response, making them susceptible to recurrent and severe infections. This blog delves into the intricacies of X-CGD, exploring its causes, symptoms, diagnosis, and management strategies.
Genes Involved
X-CGD is caused by mutations in genes responsible for producing enzymes involved in the NADPH oxidase complex. This complex is crucial for the production of reactive oxygen species (ROS), which are essential for killing invading microbes. The most commonly affected gene is CYBB, also known as gp91phox. Other genes involved include CYBA, NCF1, NCF2, NCF4, and RAC1.
Recognizing the Signs and Symptoms
X-CGD can manifest with a wide range of symptoms, often starting in early childhood. Common signs include:
- Recurrent bacterial and fungal infections: These infections can affect various parts of the body, including the lungs, skin, lymph nodes, and bones.
- Abscesses: These are collections of pus that form in tissues due to infection.
- Pneumonia: Inflammation of the lungs, often caused by bacteria.
- Granulomas: These are small, inflammatory nodules that can form in various organs.
- Delayed wound healing: Wounds may take longer to heal due to impaired immune function.
- Hepatosplenomegaly: Enlarged liver and spleen.
Causes
X-CGD is caused by mutations in genes responsible for producing enzymes involved in the NADPH oxidase complex. This complex is crucial for the production of reactive oxygen species (ROS), which are essential for killing invading microbes. These mutations are inherited in an X-linked recessive pattern.
Inheritance/recurrence risk
X-linked recessive inheritance means that the defective gene is located on the X chromosome, one of the two sex chromosomes. Females have two X chromosomes, while males have one X and one Y chromosome. Females are carriers if they have one copy of the defective gene, while males will have the disease if they inherit the defective gene from their mother. The risk of having a child with X-CGD is 50% for each pregnancy if the mother is a carrier. If the father has X-CGD, all daughters will be carriers and no sons will have the disease.
