Alpha-1 antitrypsin deficiency is a genetic condition. The Alpha-1 gene has over 100 variants. Some of these variants stop your body from producing enough normal Alpha-1. These gene variations are known as “alleles”.

The normal variant of the Alpha-1 gene is labeled “M”. Two of the most common variants that increase your risk for lung or liver disease are labeled “S” and “Z”. Since everyone has two of these genes (one from each parent), there are multiple combinations.

Here are the possible combinations of M, S, and Z genotypes:

  • MM genotypes do not have Alpha-1 deficiency.
  • MS and SS genotypes are variants. However, they don’t lower your Alpha-1 level enough to cause disease. That means typically if you are an MS or SS you won’t need specific Alpha-1 therapy.
  • MZ genotype means you have one copy of the “Z” allele. With a “Z” allele, you have an increased risk of lung and liver disease.
  • ZZ and SZ genotypes are affected by Alpha-1. If you are ZZ, you have two deficiency variants (alleles). This means you are at risk for lung and liver disease.

Why do Risk Factors Matter?

Alpha-1 antitrypsin deficiency does not cause damage by itself. The alpha-1 antitrypsin protein (AAT) is produced by your liver and helps protect your lungs from damage and irritants like smoke.

Without enough AAT circulating in the blood, your lungs are at higher risk for disease. You may develop COPD, particularly if you have other risk factors.

When you have a Z gene type, most of that AAT protein is stuck in the liver and can cause damage to liver cells.  Risk factors like drinking alcoholic beverages, exposure to some drugs and your diet can increase the chances of liver disease.

Knowing your genotype will also help you learn if your children or other family members are likely to be affected by Alpha-1. That’s why it’s so important to get tested.

To learn more about Alpha-1 gene types, visit the Big Fat Reference Guide to Alpha-1 (BFRG). If you are enrolled in AlphaNet’s Subscriber Portal, you can access the BFRG at