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Alpha-1 antitrypsin deficiency (AAT deficiency, or AATD) is an inherited condition that raises the risk of lung and liver disease. People who have it do not make enough alpha-1 antitrypsin (AAT), a protein made in the liver that protects the lungs from inflammation and from irritants such as smoke. Without enough of it, smoking, pollution or environmental dust can damage the lungs more easily, leading to chronic obstructive pulmonary disease (COPD). AAT deficiency can also cause cirrhosis of the liver, which is more common in children who have the condition.
How it is inherited
AAT deficiency is genetic. It is caused by changes, also called variants or mutations, in the SERPINA1 gene, which carries the instructions for making AAT. Because the changes are passed down from parents, the condition runs in families.
- Two changed copies of the gene means having AAT deficiency. People with it are at higher risk of lung disease or liver damage before age 45.
- One changed copy makes someone a carrier, at slightly higher risk of lung disease, especially if they have other risk factors such as smoking. Carriers can pass the gene to their children.
The gene changes that cause AAT deficiency can reduce how much AAT the liver makes, stop it being made at all, or change the protein's shape so it cannot leave the liver to protect the lungs. In that last case, AAT builds up in the liver over time and damages it.
Symptoms
Some people have no symptoms. When symptoms do appear, it is usually between ages 20 and 50. They can include:
- wheezing, and shortness of breath, especially after exercise
- a chronic cough with phlegm
- repeated respiratory infections such as colds and flu
- chest pain and fatigue
- a faster-than-normal heartbeat on standing
- vision problems
- losing weight without trying
Some people have liver damage, with jaundice (yellowing of the skin and eyes) and swelling in the legs. Rarely, AAT deficiency causes skin problems such as painful lumps or patches.
Diagnosis
A provider may test for AAT deficiency in someone who has its symptoms, a condition that could be related to it, or relatives with AAT deficiency or with a lung or liver disease that could be linked to it. In babies it often affects the liver, so a baby with signs of liver disease, such as jaundice or abnormal liver enzyme tests, may need testing.
- A blood test measures the level of AAT. A lower-than-normal level makes AAT deficiency likely.
- A genetic test is the most certain way to confirm it and should follow the blood test. A genotype test looks for the more common gene changes; a phenotype test checks for changes that stop the AAT protein working normally.
- Lung function tests show how well the lungs are working, if they are affected.
Treatment
There is no cure, but treatment can ease symptoms and slow lung damage:
- inhaled medicines to help breathing
- pulmonary rehabilitation
- oxygen therapy
- augmentation therapy, a lifelong treatment that raises AAT levels in the lungs using AAT from donated blood. It slows lung damage but cannot prevent liver damage.
- lung surgery or a lung transplant, if the lungs are badly damaged
- a liver transplant, if the liver is badly damaged
To prevent or delay lung damage, quit smoking and avoid secondhand smoke, dust and air pollution. Ask a provider whether you need to stop drinking alcohol.
Sources
- MedlinePlus (National Library of Medicine), "Alpha-1 Antitrypsin Deficiency." https://medlineplus.gov/alpha1antitrypsindeficiency.html
- The source once writes "ATT protein" for AAT protein; it is corrected here.
Лицензия: CC0 1.0 (общественное достояние) · По материалам medlineplus.gov
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