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SERPINA1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SERPINA1 gene

The SERPINA1 gene provides instructions for producing alpha-1 antitrypsin, a protein that protects the lungs from damage by inhibiting specific enzymes.

Normal Function

The SERPINA1 gene provides instructions for making a protein called alpha-1 antitrypsin, which is a type of serine protease inhibitor (serpin). Serpins help control chemical reactions by blocking the activity of certain enzymes. Alpha-1 antitrypsin primarily inhibits the digestive enzyme trypsin and a powerful enzyme called neutrophil elastase, which is released from white blood cells to fight infection.

Produced in the liver and transported through the blood, alpha-1 antitrypsin protects the lungs from neutrophil elastase, which can damage lung tissue if not properly controlled.

Health Conditions Related to Genetic Changes

Alpha-1 antitrypsin deficiency

More than 100 variants in the SERPINA1 gene are associated with alpha-1 antitrypsin deficiency, a condition characterized by a shortage of the protein that increases the risk of lung and liver disease. The condition is influenced by different alleles:

  • M allele: The unaltered, normal version of the gene.
  • Z allele: A common variant (Glu342Lys) that produces abnormal proteins that can form large molecules (polymers) in the liver, causing liver damage and reducing the amount of functional protein available to protect the lungs.
  • S allele: A variant (Glu264Val) that produces an abnormal form of the protein that is quickly broken down in the liver.

In some cases, gene variants prevent the production of any alpha-1 antitrypsin protein, leaving the lungs unprotected from neutrophil elastase even if the liver remains healthy.

Other Names for This Gene

  • A1A
  • A1AT
  • A1AT_HUMAN
  • AAT
  • alpha-1 antiproteinase
  • alpha-1 antitrypsin
  • alpha-1 proteinase inhibitor
  • alpha1AT
  • PI
  • PI1
  • protease inhibitor 1 (anti-elastase)
  • serine protease inhibitor, clade A (alpha-1 antiproteinase, antitrypsin), member 1
  • serpin peptidase inhibitor, clade A (alpha-1 antiproteinase, antitrypsin), member 1

Frequently Asked Questions

level of 50 mg/dL is below the normal reference range (typically 80–200 mg/dL) and indicates a significant deficiency. In someone with a Z allele, this suggests that most of the protein is trapped in the liver and not released into circulation, increasing the risk for lung and liver disease. Your clinician may recommend regular lung function tests and liver imaging, and consider augmentation therapy if levels remain low.
First‑degree relatives (parents, siblings, children) should be offered testing after the index case is diagnosed, especially if they have respiratory symptoms, a family history of early‑onset COPD, or liver disease. Early identification allows for monitoring and preventive measures.
void smoking and second‑hand smoke, stay away from occupational dusts, fumes, and chemical irritants, and keep up with vaccinations (influenza and pneumococcal) to reduce respiratory infections. Regular exercise and a balanced diet can also support overall lung health.
ugmentation therapy delivers purified alpha‑1 antitrypsin intravenously to raise blood levels. It is typically recommended for patients with severe deficiency (often Z/Z genotype) who have evidence of progressive emphysema, a low baseline lung function (FEV1 < 50 % predicted), and no contraindications. The goal is to slow lung function decline and reduce exacerbations.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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