Do people with alpha-1 antitrypsin deficiency always have symptoms?
Some people with alpha-1 antitrypsin deficiency (AATD) have no symptoms for some or all of their lives. The chance that someone will get symptoms depends on their AATD genetic makeup and their lifestyle habits, such as smoking. AATD is caused by changes, or mutations, in the SERPINA1 gene. AATD is inherited in an autosomal recessive manner, so people with the condition have mutations in both copies of their SERPINA1 gene. There are different versions, or alleles, of the SERPINA1 gene (also called "PI" types). The most common allele is the "M" allele, and having two of these leads to the usual amount of alpha-1 antitrypsin in the blood and no symptoms of AATD. The "S" allele leads to medium-low levels of alpha-1 antitrypsin protein. The "Z" allele leads to very low levels of alpha-1 antitrypsin protein. People with "SZ" alleles can have some symptoms of AATD. Having "ZZ" alleles leads to more symptoms of AATD. AATD carriers are those who have a mutation in one copy of their SERPINA1 gene (usually "MZ" alleles).
The risk for lung disease in alpha-1 antitrypsin deficiency (AATD) increases with age. The lifetime risk for emphysema in people with SZ alleles is estimated to be 20-50%. The lifetime risk for emphysema in people with ZZ alleles is estimated to be 80% or higher. The risk for liver disease is highest in people with ZZ alleles. Up to 40% of infants with ZZ alleles may have abnormal liver function; however 2.4% of these infants experience life-threatening liver disease that may be treated by liver transplantation or result in death. Liver disease is less common in older children and young adults. 10-40% of adults over the age of 40 with ZZ alleles will have liver disease to a varying degree. This is usually liver cirrhosis, and hepatocellular carcinoma (a liver cancer) is a rare complication. A few people with AATD, especially non-smokers, can live a normal length of life without developing symptoms of AATD.
Alpha-1 Antitrypsin Deficiency. GeneReviews. Retrieved August 28, 2017 from https://www.ncbi.nlm.nih.gov/books/NBK1519/
CHEST Foundation. Alpha-1 Antitrypsin Deficiency. Retrieved from http://www.chestnet.org/Foundation/Patient-Education-Resources/Alpha1-Antitrypsin-Deficiency.