Common Variable Immunodeficiency: Overview and More

Common variable immunodeficiency (CVID) is an immune system disorder that causes low antibodies, which reduces the body's ability to fight off infections. As a result, people with CVID are highly susceptible to frequent and sometimes severe infections, as well as complications from these infections.

This article provides an overview of CVID, including symptoms, causes, diagnosis, and treatment.

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Symptoms

The hallmark symptom of CVID is recurrent and potentially severe viral or bacterial infections. The precise symptoms will differ based on what type of infection the person has.

For example, different types of infections (e.g., upper respiratory tract infections, gastrointestinal infections, ear infections) will all present with very different symptoms. However, it is the frequent recurrence of these infections that indicates a warning sign for CVID, rather than any exact symptoms of the infection itself.

Some symptoms of CVID might include:

Due to the frequency and/or severity of infections, a person with CVID is also at risk for certain complications. The most common CVID complications include:

Prevalence of CVID

CVID is the most common primary immunodeficiency, but this does not mean it is a common disorder. Estimates vary, but it is thought that CVID occurs in anywhere from one in 10,000 to one in 50,000 people.

Causes

CVID is thought to be caused by mutations in certain genes that impact the immune system—in particular, mutations in the genes that influence the production, maturation, and function of B-cells.

B-cells are a type of white blood cell that produces antibodies. Antibodies are the Y-shaped proteins that help us fend off infections. CVID causes a deficiency in these antibodies.

Over 20 different genetic mutations have been identified so far as either causing CVID or increasing a person's risk of developing CVID. The most common are mutations in the TNFRSF13B gene (approximately 8% of CVID cases) and the NFKB1 gene.

Most of these genetic mutations occur sporadically, but some may be passed down through families. This can occur through both dominant and recessive inheritance.

However, it is important to note that identified genetic mutations only explain 10% to 20% of CVID cases. For the majority of people with CVID, there is no identifiable cause.

This leads researchers to believe that environmental factors play a role in causing CVID, although we do not know at this time what these environmental factors might be. There are also likely many other genes that cause CVID that have yet to be identified.

Diagnosis

After gathering a health history of recurrent infections, CVID can be diagnosed through a series of blood tests.

These include tests such as:

To be diagnosed with CVID, a person must have low immunoglobulins (antibodies). This includes low IgG and either IgM or IgA. It also requires a poor response to vaccines and the absence of any other disorder that causes an immunodeficiency.

Diagnostic Delay

Getting diagnosed with CVID can be challenging in multiple ways:

A person may become accustomed to their frequent infections and think of them as a "fact of life," and subsequently delay seeking medical care.
As a relatively rare disorder, many health providers do not know enough about CVID to properly diagnose it.
CVID mimics other conditions and, as a diagnosis of exclusion, can only be diagnosed once these conditions are ruled out, which can complicate diagnosis.
Finally, in the past even experts had disagreed on the diagnostic criteria for CVID, such as whether a poor vaccine response is required to have CVID.

As a result, diagnosis can be delayed from four to nine years after symptoms begin.

This is a significant issue, because the longer CVID goes untreated, the more complications can form, which can impact life expectancy. Therefore, it's essential to receive a timely, accurate diagnosis if you have symptoms of CVID.

Treatment

The mainstay treatment for CVID is immunoglobulin (antibody) replacement therapy. This uses the blood donations from healthy individuals and essentially restores the antibodies in a person's body to a normal level so they can better fight off infections.

Immunoglobulin replacement therapy can be given either through intravenous (IV) infusions or subcutaneous injections. The exact frequency and dosage should be determined individually, based on the person's antibody level response. Treatment is lifelong.

Another aspect of CVID treatment is treating any active infections. Even with immunoglobulin replacement therapy, a person with CVID may experience more infections than the average person. This treatment will depend on what kind of specific infection the person has, but may include antibiotics, antivirals, over-the-counter (OTC) therapies, and more.

Prognosis

The good news is that life expectancy for those who have CVID has significantly improved in the last 30 years, from just 12 years post-diagnosis to over 50 years. This is thanks, in large part, to the pioneering of immunoglobulin replacement therapy as a CVID treatment.

However, some factors may reduce a person's life expectancy. These include:

Higher age at diagnosis
Lower B-cells
Lower baseline IgG at diagnosis
Complications such as structural lung damage (bronchiectasis or granulomas), chronic hepatitis, lymphoma, or chronic gastrointestinal diseases

As a result, it's important to receive a prompt diagnosis of CVID to prevent these complications.

The majority of people receiving immunoglobulin replacement therapy find they have fewer infections and a higher quality of life.

Summary

Common variable immunodeficiency is a disorder of the immune system that is characterized by low antibodies. It reduces the body's ability to fight off infections, so frequent and recurring infections occur. The main treatment option is immunoglobulin (antibody) replacement therapy, but any infections that result from CVID must be treated as well.

A Word From Verywell

It's possible to live a full and active life with CVID, but it will take some adjustments. These include regular treatment with immunoglobulin replacement therapy, as well as lifestyle modifications to prevent infections. Finding a healthcare provider to help with either diagnosing or managing your CVID is an important first step in living with this condition.

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