WITH 4,300 patients registered on the UK Primary Immunodeficiency database, numbers are small. It is estimated that PIs affects around 5,000 in England and Wales in total.

However, the number of distinct Primary Immunodeficiencies is somewhere in the region of four hundred, such that individual conditions can be so rare as to only affect one or two people worldwide.

The immune system is responsible for fighting infection, as well as destroying faulty cells, which if left unchecked may develop into cancer. Any disorder of this highly complex system is termed an immunodeficiency.

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Immunodeficiencies are divided into primary, the focus of this article, and secondary. PIs are typically due to one or more faulty genes. These can occur spontaneously or as a result of the faulty gene being inherited from a parent.

Secondary or acquired immunodeficiencies can be due to illness, or treatment such as chemotherapy. Acquired Immunodeficiency Syndrome (AIDS), is the result of untreated or uncontrolled HIV. There is no overlap between primary and secondary immunodeficiencies.

The spectrum and severity of PIs range from those diagnosed very soon after birth, to conditions which may take several years to pick up, and where the sufferer is only vulnerable to certain bugs.

Frequent bouts of severe infection that take longer to clear should raise suspicions. In addition to recurrent infections, failure to thrive is an important sign to consider..

It is estimated that delay in the diagnosis of PI may be anywhere between four to ten years in milder cases, due to PI being thought of. In addition, patients are often seen by multiple healthcare providers rather than a dedicated clinician. There is also ambiguity over what is a normal number of infections to have in any given time period. Unfortunately, during the delay in diagnosis, permanent damage can be done.

If you feel you may have PI, it is certainly worth raising this concern with your routine GP. A set of blood tests is the first step, with referral to an immunologist if appropriate.

The treatment of PIs is wide-ranging and an ever-advancing field., but if left undiscovered PI has the potential to cause significant harm.

If treated, patients can have a good quality of life, further enhanced by sensible lifestyle choices.