What are primary Immunodefiencies?
Primary immunodeficiency disorders (PIDs) form a group of rare disorders that vary widely in severity. Those at the mild end of the spectrum can predispose infants and children to frequent minor infections, while the more severe ones lead to life-threatening infections.
How does patient get PIDs?
Mostly these are inherited single-gene disorders that present in infancy in early childhood with the exception of Common variable immunodeficiency which usually occurs in adults. Mutations/deletions of genes governing stem cell differentiation have been identified and over 150 disorders have been identified.
How common is PIDs?
The overall incidence of symptomatic PIDs is estimated to be 1/10,000.About 80% of patient’s syndromes are less than 20 years old when diagnosed, because the majority of cases are inherited or congenital. 70% occur in males due to X-linked inheritance in many
What are the causes of secondary immunodeficiency?
It is known that the two current epidemics of HIV/AIDS and tuberculosis have caused global increases in this condition. Secondary immunodeficiency is also common in people who have various conditions:
- Chronic lymphatic leukaemia and multiple myeloma.
- Drugs: cytotoxic drugs and immunosuppressant including steroids.
- HIV affects T-cells.
- The commonest cause worldwide is protein-calorie malnutrition and deficiencies of vitamins and trace elements, particularly vitamin A, zinc and selenium.
- Metabolic: prolonged metabolic disorders associated with liver and kidney failure compromise immunity.
- Loss of immunoglobulin can result from a number of conditions including nephrotic syndrome, and protein-losing enteropathy.
What are the main features of PIDs?
- The commonest presenting feature and the one which usually raises the possibility of immunodeficiency are frequent infections.
- The classical picture consists of repeated episodes of sore throat or upper respiratory tract infection which lead to sinusitis, chronic otitis and bronchitis.
- Another feature is the ease with which complications develop. For example, bronchitis progresses to pneumonia, bronchiectasis and respiratory failure.
- Opportunistic infections are common, such as Pneumocystis jiroveci or cytomegalovirus.
- Infection of the skin and mucous membranes occur frequently, including resistant thrush, oral ulcers and periodontitis.
- Common gastrointestinal symptoms include diarrhoea, malabsorption and failure to thrive. The diarrhoea is usually noninfectious, although a range of organisms, including rotavirus, Giardia lamblia, rotavirus, Cryptosporidium spp and cytomegalovirus may be involved.
- Less commonly, haematological abnormalities such as autoimmune haemolytic anaemia, leucopenia, or thrombocytopenia can occur.
- Neurological problems such as seizures and encephalitis and autoimmune conditions such as vasculitis and arthritis are also sometimes seen.
How can an immunodeficiency be diagnosed?
The immune system is not located within one organ, instead cells of the immune system can be found all over the body. These cells can be measured in a blood sample and their ability to function properly can be analyzed in laboratory tests. In addition, microscopic analysis of blood, bone marrow and lymph nodes can yield important information. Often genetic analysis is necessary to determine a specific immunodeficiency.
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