One of the less well known forms of primary immunodeficiency is called activated PI3K delta syndrome (APDS). It is a rare disease that has only recently been identified by scientists. While there is still much work to be done in understanding that nature of the syndrome, researchers are searching for ways to learn more about it and distinguish it from related diseases such as common variable immunodeficiency (CVID).
What is Activated PI3K Delta Syndrome?
As in many forms of immunodeficiency, activated PI3K delta syndrome causes patients to have weakened immune systems, and their levels of white blood cells, such as B cells and T cells, are often abnormally low. The syndrome is linked to mutations affecting a gene called PIK3CD, which plays a critical role in the creation of a protein called p110 delta. This protein is in turn part of the enzyme phosphatidylinositol 3-kinase (PI3K). This enzyme is critical for the activation of important signaling pathways for T cells and B cells. Without it, the proper amount of these cells cannot mature and proliferate. Activated PI3K delta syndrome is inherited in an autosomal dominant pattern, meaning that only a single copy of the mutated gene per cell is sufficient to trigger symptoms.
Symptoms appear early in life and often include frequent infections. These infections are most common in the sinuses, ears, and lungs. A variety of pathogens may be active in these infections, and chronic viral infections involving the Epstein-Barr virus (EBV) and cytomegalovirus can appear. In many cases, the rate of infections affecting the lungs can lead to the condition called bronchiectasis, which can trigger long term breathing issues. Activated PI3K delta syndrome can also cause white blood cells to form into abnormal clumps, which can accumulate in the linings of the intestines or airway. They can also cause the lymph nodes to enlarge, and patients also have an increased risk of B-cell lymphoma.
Unfortunately, difficulty in diagnosing the disease means that its true prevalence remains unknown. Unfortunately, treatment is almost entirely symptomatic and requires frequent use of antiviral and antibiotic therapies to combat the frequent infections. Ultimately, all measures possible should be taken to avoid exposure to infections.
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