What is Primary Immunodeficiency (Primary PIDs)?
Primary immunodeficiency disorders (PIDs) are rare disorders that present acutely. Those at the severe end of the spectrum can expose infants and children to less frequent infections, but severe primary immunodeficiency leads to life-threatening infections for the affected individual.
How does a patient develop primary immunodeficiency disorders?
These disorders are mostly inherited as single-gene disorders. They occur in early childhood, affecting infants, with the exception of common variable immunodeficiency, which usually occurs in adults. Genetic deletion mutations that regulate stem cell differentiation have been identified, and more than 150 immune disorders have been recognized.
How common are primary immunodeficiency disorders?
The overall estimated incidence of symptomatic primary immunodeficiency disorders is 1/10,000. About 80% of patients are under 20 years of age when diagnosed. This is because the majority of cases result from genetic or congenital factors. In many cases, 70% of cases occur in males, as most cases are inherited or congenital. 70% occur in males due to X-linked recessive inheritance.
What are the causes of secondary immunodeficiency?
It is known that the current HIV/AIDS and tuberculosis pandemics have led to an increase in cases suffering from this disease worldwide. Secondary immunodeficiency is also a condition seen in people with various conditions, including:
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Chronic lymphocytic leukaemia and multiple myeloma.
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Drugs and medications: Cytotoxic drugs and immunosuppressants, including steroids.
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HIV, which affects T cells.
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The most common cause worldwide is malnutrition resulting from protein-energy deficiency and deficiencies of vitamins and trace elements, especially vitamin A, zinc, and selenium.
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Long-standing metabolic disorders accompanied by failure of liver and kidney function and associated with immunity.
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Immunoglobulin loss can result from several conditions, including nephrotic syndrome and protein-losing enteropathy.
What are the main features of primary immunodeficiency disorders?
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Recurrent infections are one of the most common main features and symptoms indicating the possibility of acquired immunodeficiency.
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The classic picture consists of recurrent episodes of pharyngitis or upper respiratory tract infection leading to otitis media, chronic sinusitis, and bronchitis.
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Another feature is the ease with which complications develop. For example, bronchitis progressing to pneumonia, bronchiectasis, and respiratory failure.
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Opportunistic infections are common, such as Pneumocystis jirovecii pneumonia or cytomegalovirus.
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Frequent infections of the skin and mucous membranes occur, including resistant thrush and mouth and gum ulcers.
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Common gastrointestinal symptoms include diarrhoea, malabsorption, and failure to thrive. The diarrhoea is usually not infectious, though a range of organisms may have an effect, including rotavirus, Giardia lamblia, and Cryptosporidium.
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Less commonly, haematological abnormalities can occur, such as autoimmune haemolytic anaemia and thrombocytopenia.
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Neurological problems such as epilepsy and encephalitis, as well as autoimmune diseases such as arthritis and vasculitis, may also be observed.
How is immunodeficiency diagnosed?
The immune system is not contained within a single organ, and immune system cells can be found throughout the body. These cells can be measured by taking a blood sample, and their ability to function correctly can be analysed in laboratory tests. In addition, microscopic analysis of blood, bone marrow, and lymph nodes can provide highly important information. Genetic analysis is often necessary to identify a specific immunodeficiency.
