Alpha-1-antitrypsin deficiency (A1A)

  • This page explains alpha-1-antitrypsin deficiency and its effects, including the symptoms, how it is diagnosed and options for treatment.

    What is alpha-1-antitrypsin?

    Alpha-1-antitrypsin (A1A) is a protein, produced by the liver, which is found in your bloodstream. Its main role is to protect your lungs from destruction by other proteins called enzymes.

    Enzymes are found in all parts of the body and are needed for digestion to ensure that chemical reactions in your body take place normally. Enzymes have many important roles in the lung, particularly in removing bacteria and in fighting infections. The A1A protein is needed to balance this enzyme activity to prevent lung tissue being damaged.

    What is alpha-1-antitrypsin deficiency (A1AD)?

    A1AD is a rare, genetically inherited condition that affects around one in 3,000 to one in 4,000 people in the UK. To inherit the condition, an abnormal gene must be passed on by both parents.

    The condition means you have a low level, or ‘deficiency’, of the alpha-1-antitrypsin protein in your blood. If you carry only one abnormal gene this does not appear to cause disease in its own right as the level of A1A in the blood is high enough to carry out its role.

    The deficiency becomes important only when the concentration in your blood is 10-20 per cent of what we would normally expect.

    When A1A levels get this low, your lungs struggle to defend themselves against enzymes. This means the enzymes can begin to destroy healthy lung tissue, especially if you smoke, causing emphysema.

    Emphysema is one of the lung conditions covered by the term chronic obstructive pulmonary disease (COPD).

    What are the symptoms?

    Patients are born with A1AD, but symptoms rarely start before the age of 20 years and more commonly start after 40.

    The deficiency leads to early onset COPD, especially in people who smoke. In people who do not have A1AD, symptoms of COPD do not normally develop until after the age of 50.

    But in people with A1AD, symptoms can develop much sooner, as the disease tends to progress more rapidly. People who smoke and have A1AD may develop symptoms in their 20s, while non-smokers with A1AD are more likely to experience symptoms from the age of 40 onwards.

    The symptoms of A1AD are due to the COPD and the main ones are:

    • persistent breathlessness
    • wheeze
    • cough

    Not everyone with the condition A1AD will go on to develop COPD. There are many gene variations and only people with the lowest blood levels of A1A are likely to develop disease. At present it is not known what proportion of people with A1AD will develop COPD, but it is likely that the majority remain well.

    Liver failure can be a problem in a few children with A1AD, but after childhood the life expectancy in healthy non-smokers with A1AD is essentially normal.

    A1AD may also be associated with jaundice (yellowing of the skin and eyes) in newborn babies and although most people with A1AD develop some liver scarring, only a small proportion of people develop symptoms of liver disease and the majority remain healthy.

    How is it diagnosed?

    The main condition that may be confused with A1AD is asthma. Doctors should check for A1AD in anyone under the age of 40 who has persistent breathlessness, wheeze or cough. The diagnosis can be made by a simple blood test to measure the level of A1A in the blood. If the level is low, further tests will indicate how bad the deficiency is.

    If a diagnosis of A1AD is made then family members, and particularly siblings, should be tested to look for anyone else who may have undiagnosed deficiency or disease.

    Can I be treated for A1AD?

    There is no specific approved treatment yet. However, if you smoke, it is very important that you stop. This will slow down the development of COPD.

    COPD caused by A1AD can be treated in the same way as COPD that is not caused by A1AD, for example with an inhaler to ease breathlessness and with pulmonary rehabilitation. Pulmonary rehabilitation is a programme carefully tailored to you as an individual. It includes exercise, information on COPD and its management, as well as how to cope with breathlessness.

    Detailed advice about these treatment options is available in the British Lung Foundation’s information on COPD.

    A healthy lifestyle, including eating plenty of fruit and vegetables and taking regular exercise, is recommended. You should try to avoid chest infections by having an annual flu jab and by staying away from friends or family when they have infections.

    In people with COPD, chest infections lead to a quicker decline in your lung function. If you have a cough that produces green sputum (phlegm) you should see your doctor, as you may have an infection and a course of antibiotics may be needed.

    A pneumococcal vaccination is also recommended.

    Since people with A1AD often develop COPD earlier in life, a lung transplant may be an option for some people with severe lung disease.

    Possible future treatments

    The current medical approach to A1AD is that, if it were possible to ‘top-up’ the body with protein, the progression of COPD might be slowed.

    This treatment – a drug called Prolastin – is available in many countries, but not in the UK. It has to be given by weekly injection and is very expensive. A recent review of the two clinical trials so far performed concluded that there was no clinical benefit from the drug and that it could not be recommended.

    However, the review has received some criticism. The two studies quoted in the review and lots of observation of patients suggest that the treatment may benefit some people. This is currently being examined by experts in more detail.

    Other studies of drugs that may be able to repair the lungs are ongoing. Research into correcting the gene that leads to a lack of A1A has also begun.

    Further information

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    Code: IS3
    Last medically reviewed: September 2011
    Due for medical review: September 2013
    For references call 020 7688 5610 or email


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