Genetics of
Alpha-1 Antitrypsin Deficiency

Know the letters behind the Alpha-1 diagnosis.

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The Alpha-1 gene is passed down through families

Your doctor is always the best source of information when it comes to understanding your test results and alpha-1 antitrypsin (A1AT) deficiency genetics. The following gives you a brief overview of the most common genetic variations or labels associated with Alpha-1 to help you better understand your condition.

Alpha-1 is a genetic disorder.1 The condition is passed down over generations through our genes—the same things that give us our eye and hair color. Each person receives 2 genes that affect the body’s production of A1AT: one from each parent. The most common gene is the M gene. The common disease-causing genes are S, Z, and NULL.2 The combination of these genes determines the severity of the condition.

More common than you realize3

  • Americans is estimated to have the SS, SZ, or ZZ gene pairs.
  • Americans carries an S and/or Z gene.

Several scenarios for how Alpha-1 can be passed down through families

How Alpha-1 can be passed down through families
  • Normal

    With 2 M genes, there is minimal to no risk of developing symptoms of Alpha-1 because both genes are normal.4

  • Abnormal

    With the S gene, there may not be any symptoms.

    May have mild to moderate symptoms, depending on the second gene.4

  • Abnormal

    With the Z gene, symptoms may be more severe.

    May be at risk for Alpha-1, depending on the second gene.4

Not seeing your letters?

You may have a rare variant. If you do not see your letters, please contact the Alpha-1 Genetic Counseling Center at 1-800-785-3177 to learn more about your Alpha-1 test results.

“M means normal”

  • M alleles. M alleles are the normal forms of the gene. If you have 2 M genes, you do not have an A1AT deficiency.2, 4

“S, Z, and NULL mean abnormal”

  • S variants. If you have an S variant, you have an abnormal gene and may be at risk for developing mild to moderate symptoms.2, 4
  • Z variants. If you have a Z variant, you have an abnormal gene and are at risk for a serious Alpha-1–related disease, even if you have a normal allele from your other parent. People with 2 Z variants have severe Alpha-1.2, 4
  • NULL variants. These variants are very rare. People with 2 NULL variants cannot make any A1AT.2, 4
  • Rare variants. According to the American Thoracic Society, over 30 rare variants have been identified that may put you at risk for Alpha-1–related disease.5

Important Safety Information

Alpha1-Proteinase Inhibitor (Human), Zemaira® is indicated to raise the plasma level of alpha1-proteinase inhibitor (A1-PI) in patients with A1-PI deficiency and related emphysema. The effect of this raised level on the frequency of pulmonary exacerbations and the progression of emphysema have not been established in clinical trials.

Zemaira may not be suitable for everyone; for example, people with known hypersensitivity to components used to make Zemaira, those with a history of anaphylaxis or severe systemic response to A1-PI products, and those with certain IgA deficiencies. If you think any of these may apply to you, ask your doctor.

Early signs of hypersensitivity reactions to Zemaira include hives, rash, tightness of the chest, unusual breathing difficulty, wheezing, and feeling faint. Immediately discontinue use and consult with physician if such symptoms occur.

In clinical studies, the following adverse reactions were reported in at least 5% of subjects receiving Zemaira: headache, sinusitis, upper respiratory infection, bronchitis, fatigue, increased cough, fever, injection-site bleeding, nasal symptoms, sore throat, and swelled blood vessels.

Because Zemaira is made from human blood, the risk of transmitting infectious agents, including viruses and, theoretically, the Creutzfeldt-Jakob disease (CJD) agent, cannot be completely eliminated.

Please see full prescribing information for Zemaira.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit, or call 1-800-FDA-1088.

CSL Behring

Zemaira is manufactured and distributed by CSL Behring LLC.
Zemaira® and CareZ® are registered trademarks of CSL Behring LLC.

© 2018 CSL Behring. The product information presented on this site is intended for US residents only.
ZMR14-04-0006d 12/2014