#Alpha1AntitrypsinDeficiency#A1AT
What is alpha-1 antitrypsin deficiency (A1AT)?
Alpha-1 antitrypsin deficiency, also called A1AT, AAT deficiency, and alpha-1, is a rare genetic disorder that causes low levels of the protein alpha-1 antitrypsin in the blood. A1AT can cause lung and liver disease. Approximately one in 1,500 to 3,500 individuals with European ancestry have A1AT, but it is estimated that 185 million people worldwide are carriers. A1AT is likely underdiagnosed, with some people with the deficiency never receiving a diagnosis or being diagnosed with chronic obstructive pulmonary disease (COPD) without an underlying cause. Others are misdiagnosed with asthma.
What are the symptoms of A1AT?
The symptoms of lung disease caused by A1AT are very similar to those caused by COPD. The symptoms usually start between the ages of 30 and 50 and can include the following:
- Shortness of breath (dyspnea)
- Wheezing
- Chronic cough, usually with mucus
- Recurrent chest colds and other respiratory infections
- Exercise intolerance
- Fatigue
- Unintentional weight loss
Approximately 10% of infants and 15% of adults with A1AT develop liver disease. Signs and symptoms of this manifestation of A1AT include the following:
- Yellowing of the skin and eyes (jaundice)
- Itchy skin
- Swelling of the abdomen (ascites) or legs and feet
- Blood in vomit or stool
- Unexplained elevated liver enzymes
- Fatigue
- Loss of appetite
- Unintentional weight loss
In rare cases, A1AT can lead to panniculitis, a skin condition characterized by patches of painful, hard, red bumps that may leak fluid or pus.
What causes A1AT?
A1AT is caused by mutations in the SERPINA1 gene. This gene codes the protein alpha-1 antitrypsin, also called AAT, which protects healthy tissue from being attacked by neutrophil elastase, an enzyme white blood cells release to fight infection, especially in the lungs. If not controlled by alpha-1 antitrypsin, neutrophil elastase will finish fighting the infection and then attack healthy cells. Variants in the SERPINA1 gene can cause a shortage of alpha-1 antitrypsin or create an abnormal version of the alpha-1 antitrypsin protein. Without a normal level of functioning alpha-1 antitrypsin, there is nothing to stop neutrophil elastase from fighting healthy tissue and damaging the alveoli in the lungs, causing lung diseases such as emphysema. The AAT protein is primarily produced in the liver. Abnormal AAT cannot be released by the liver and move to the lungs at a normal rate, which causes a buildup of abnormal protein in the liver that can lead to scarring and disease (cirrhosis).
A1AT is inherited in an autosomal codominant pattern, which means that two different versions (alleles) of the SERPINA1 gene can be expressed at the same time and both alleles influence how someone makes alpha-1 antitryptase. The most common allele, M, produces normal levels of the alpha-1 antitrypsin protein, and most people will have two M genes (MM), meaning they do not have A1AT. The S allele produces low levels of the protein and the Z allele produces even less than that. The most common gene combination in people who have been diagnosed with A1AT is ZZ. Approximately 185 million people worldwide are either MS or MZ. These people are carriers of A1AT and are still at an increased risk of lung damage and disease.
A diagnosis of A1AT starts with a blood test measuring the level of alpha-1 antitryptase in a person’s blood. If those levels are low, then genetic testing is performed to find any mutations related to A1AT. Lung and liver function tests and imagining are also done to assess any damage A1AT might have caused.
How do you treat A1AT?
While there is no cure for A1AT, treatment is available depending on a person’s symptoms and the extent of damage to their liver and lungs. If someone has lung conditions caused by A1AT, then their doctor can treat them with medications used for COPD, such as bronchodilators and pulmonary rehabilitation. If someone has severe A1AT that has caused emphysema, then they may receive augmentation therapy. In augmentation therapy, normal alpha-1 antitrypsin protein is taken from healthy donor blood plasma and given to someone with A1AT via intravenous (IV) infusion, which then increases (augments) the levels of alpha-1 antitrypsin in the recipient’s blood and lungs. Augmentation therapy cannot reverse lung damage that has already happened, but it can prevent further lung damage, however it does not prevent liver damage. A person with lung disease caused by A1AT may receive oxygen therapy, inhaled corticosteroids, and, if they are unable to stop smoking, smoking cessation therapy. In some cases of extreme lung or liver damage, a transplant may be recommended. It’s important for people with A1AT to have regular appointments with their medical providers and receive the appropriate vaccinations, as well as avoid exposure to inhaled irritants and pollutants, such as cigarette smoke.
The prognosis for A1AT varies widely from person to person. Some people with A1AT may experience little to no symptoms while others could experience severe complications. It’s important for everyone with A1AT to work with their doctor to create an individualized treatment plan.
Information provided in part by MedlinePlus, Cleveland Clinic, and the Alpha-1 Foundation.
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