How Do Genetics Play a Role in Alpha-1 Protein Levels?
Here's what you'll learn on this page:
Your genotype determines how much alpha-1 protein your body makes—common alleles range from M (normal) to Z and Null (undetectable amount), with ZZ producing severely deficient levels
What is a normal alpha-1 antitrypsin level? Normal alpha-1 protein levels are 20 μM or higher
Lower levels may mean higher risk, and lung damage can begin before symptoms appear
Risk varies on a spectrum based on your individual protein levels, environmental exposures, and lung health history
Alpha-1 affects people differently, and your genotype determines how much alpha-1 protein your body has, and how much risk your lungs have.
What does your genotype mean for you?
Your Alpha-1 genotype is made up of 2 alleles—1 inherited from each parent. Some of the different alleles include:
M
Normal amount of working alpha-1 protein
S
Some alpha-1 protein, but less than normal
Z
Very little working alpha-1 protein
Null
No working alpha-1 protein
Typical alpha-1 protein level ranges by genotype
Normal alpha-1 protein levels are 20-53 μM. In addition to lifestyle and environmental factors, lower alpha-1 protein levels can lead to greater risks.
Understanding your level of risk
When alpha-1 protein levels are below normal, there may not be enough alpha-1 protein to help protect the lungs from neutrophil elastase, an enzyme that can damage healthy lung tissue when it becomes overactive. Over time, this may increase the risk of lung damage and related breathing problems.
*A group of conditions characterized by inflammation of the blood vessels, causing them to thicken, narrow, or weaken.
While your risk varies along a spectrum, if your genotype is ZZ, your body has very low alpha-1 protein levels. This means you have severely deficient alpha-1 protein levels.
Why do your alpha-1 protein levels matter?
Alpha-1 protein levels and the protection they provide can differ from person to person, even those with the same genotype, based on different lifestyle factors.
You may feel fine today, but your alpha-1 protein levels could still be lower than what your lungs need to stay protected. When levels fall below normal, your lungs may be exposed to ongoing damage, even before symptoms appear.
Understanding where your alpha-1 protein levels fall helps clarify your personal risk.
Frequently asked questions
Is Alpha-1 antitrypsin deficiency hereditary?
Yes. Alpha-1 antitrypsin deficiency (Alpha-1) is an inherited condition, which means it's passed down through families. It's caused by changes in a gene called SERPINA1—the gene that gives your body instructions for making alpha-1 antitrypsin (AAT), the protein that helps protect your lungs.
You inherit one copy of this gene from each parent. The combination you receive helps determine how much alpha-1 protein your body has and whether your levels fall within or below the normal range.
What is an Alpha-1 carrier?
A carrier is someone who has inherited one typical gene copy (usually written as M) and one altered copy (such as S or Z). For example, an MZ or MS combination.
Carriers often have an alpha-1 protein level that stays within or near the normal range, and many never experience symptoms. But because they carry an altered gene, they can pass it on to their children. If you're a carrier, it can be helpful to talk with your doctor, especially when it comes to family planning or understanding your own risk over time.
Do both parents have to have Alpha-1 for a child to inherit it?
Not necessarily—it depends on which genes each parent passes down.
- If a child inherits an altered gene from each parent (for example, 2 Z copies, or ZZ), they may develop Alpha-1 with below-normal protein levels
- If a child inherits one altered gene and one typical gene (like MZ), they're usually a carrier—they may have somewhat lower levels but often don't develop the condition
So a child can inherit altered genes even if neither parent has noticeable symptoms. That's one reason testing and family conversations can be so valuable—they help you understand your full picture.