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SERPING1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SERPING1 gene

The SERPING1 gene provides instructions for making the C1 inhibitor protein, which regulates inflammation and blood vessel permeability by controlling specific proteins in the blood.

Normal Function

The SERPING1 gene provides instructions for making a protein called C1 inhibitor (C1-INH), which is a type of serine protease inhibitor (serpin). Serpins help control several types of chemical reactions by blocking the activity of certain proteins. C1-INH is important for controlling a range of processes involved in maintaining blood vessels, including inflammation. Inflammation is a normal body response to infection, irritation, or injury.

C1-INH blocks the activity of several proteins in the blood, including plasma kallikrein and the activated form of factor XII (called factor XIIa). These two proteins are involved in the production of bradykinin. Bradykinin is a protein fragment (peptide) that promotes inflammation by allowing fluids to leak through blood vessel walls into body tissues (vascular permeability). C1-INH attaches (binds) to plasma kallikrein and factor XIIa, which prevents them from completing any further reactions. These proteins are cleared from the bloodstream once they are bound to C1-INH.

Health Conditions Related to Genetic Changes

Hereditary angioedema

Hundreds of variants (also called mutations) in the SERPING1 gene have been found to cause hereditary angioedema, which is a disorder characterized by recurrent episodes of severe swelling (angioedema). Variants in the SERPING1 gene cause a form of the condition known as hereditary angioedema due to C1-INH deficiency. This condition is further divided into two types:

  • Type I: Occurs when the C1-INH protein levels are low.
  • Type II: Occurs when C1-INH is not functioning correctly.

The variants that cause hereditary angioedema due to C1-INH deficiency type I occur throughout the gene and lead to reduced levels of C1-INH in the blood. The variants that cause hereditary angioedema due to C1-INH deficiency type II usually occur in a specific region of the gene called exon 8. These variants lead to the production of a C1-INH that functions abnormally.

Without the proper levels of functional C1-INH, the activity of plasma kallikrein and factor XIIa cannot be blocked, and excessive amounts of bradykinin are produced. Excess fluids leak through blood vessel walls and accumulate in body tissues, leading to the recurrent episodes of swelling seen in individuals with hereditary angioedema due to C1-INH deficiency.

Other Names for This Gene

  • C1-INH
  • C1IN
  • C1INH
  • C1NH
  • complement component 1 inhibitor
  • IC1_HUMAN
  • plasma protease C1 inhibitor
  • serine/cysteine proteinase inhibitor clade G member 1
  • serpin peptidase inhibitor, clade G (C1 inhibitor), member 1

Frequently Asked Questions

HAE attacks can be triggered by stress (physical or emotional), trauma (including minor injuries, dental work, or surgery), infections, certain medications (like ACE inhibitors or estrogen-containing contraceptives), and sometimes even specific foods. To prevent or reduce frequency, individuals should identify and avoid personal triggers, manage stress, and discuss prophylactic medications with their doctor. Long-term prophylactic treatments are available to reduce attack frequency and severity.
Early signs of an HAE attack, often called prodromal symptoms, can include a tingling sensation, skin redness (erythema marginatum), fatigue, or a general feeling of unease hours before swelling appears. The most commonly affected body parts are the skin (limbs, face, genitals), gastrointestinal tract (causing severe abdominal pain, nausea, vomiting, diarrhea), and the upper airway (larynx, tongue), which is the most dangerous due to risk of suffocation.
For acute HAE attacks, on-demand treatments are available, including C1-inhibitor concentrates (plasma-derived or recombinant), bradykinin receptor antagonists, and kallikrein inhibitors. These medications help stop the progression of swelling. For long-term prevention, options include C1-inhibitor concentrates (given regularly), kallikrein inhibitors, or attenuated androgens, which aim to reduce the frequency and severity of attacks. Your doctor will determine the best treatment plan based on your specific needs.
Immediate emergency medical attention is crucial if swelling occurs in the throat, tongue, or face, as this can rapidly lead to airway obstruction and suffocation. Any severe or rapidly progressing swelling, especially if accompanied by difficulty breathing or swallowing, warrants an emergency call or visit. Severe abdominal pain that mimics a surgical emergency also requires prompt medical evaluation.
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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