An inherited disorder that can result in damage to the lungs and liver
The enzyme alpha1-antitrypsin prevents other enzymes in the body from destroying tissues, mainly those in the lungs and liver. People with alpha1-antitrypsin deficiency lack this protective enzyme due to an abnormality in a gene on chromosome 14 (called the A1AT gene) that regulates production of the enzyme. The abnormal A1AT gene is usually inherited in an autosomal recessive pattern, which means that a person must inherit one copy of the abnormal gene from each parent to develop the condition (see Gene disorders). However, there are many variants of the A1AT gene and there are therefore variations in the severity of the condition.
In severe cases, alpha1-antitrypsin deficiency causes jaundice in newborn babies (see Neonatal jaundice). However, the effects of the disorder most often appear after the age of 50 and include damage to the air sacs (alveoli) in the lungs (see Chronic obstructive pulmonary disease). Liver cirrhosis may also develop.
The diagnosis is made by measuring levels of the enzyme in the blood, and a blood test should establish if you have the genetic abnormality. Other family members may also need to be tested. If you are planning to start a family, you may wish to consult your doctor about having genetic counselling.
At present, no specific treatment for alpha1-antitrypsin deficiency is available, but trials of enzyme replacement therapy are in progress. Your doctor may prescribe inhaled bronchodilator drugs to assist your breathing. People with severe lung or liver disease may be helped by an organ transplant. You should not smoke or drink alcohol if you have alpha1-antitrypsin deficiency because these activities may cause lung and liver disease to worsen.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.