complement component 4b deficiency

Complement Component 4b Deficiency: A Rare Condition Linked to Autoimmune Disorders

Complement component 4b (C4B) deficiency is a rare genetic disorder characterized by a deficiency in the C4B protein, which is part of the complement system. The complement system is a group of proteins that play a crucial role in the immune system, helping to eliminate pathogens and foreign substances from the body.

Clinical Features

The clinical features of C4B deficiency include:

• Autoimmune disorders: C4B deficiency is linked to autoimmune disorders such as systemic lupus erythematosus (SLE) and glomerulonephritis [3].
• Recurrent infections: Some individuals with C4B deficiency may experience recurrent bacterial infections due to the impaired complement system [10].

Blood Test

A blood test, known as a complement C4 blood test, can measure the activity of the C4 protein in the blood. This test is used to look for signs of immune disorders or monitor their treatment [7][9].

Genetic Cause

C4B deficiency is caused by mutations in the C4B gene, which localizes to the RCCX locus within the major histocompatibility complex (MHC) region [5]. The genetic cause of this condition can be inherited from one's parents.

Prevalence and Heritability

Unfortunately, there is limited information available on the prevalence and heritability of C4B deficiency. However, it is considered a rare condition.

References:

[1] Clinical resource with information about Complement component 4b deficiency and its clinical features, C4B, available genetic tests from US and labs around... (Search Result 1) [3] Complement component 4b deficiency is a rare condition linked to autoimmune disorders, particularly systemic lupus and glomerulonephritis. It is also associated... (Search Result 3) [5] Deficiency of this protein is associated with systemic lupus erythematosus. This gene localizes to the RCCX locus within the major histocompatibility complex (MHC)... (Search Result 5) [7] Jan 25, 2023 — Complement component 4 is a blood test that measures the activity of a certain protein. This protein is part of the complement system. (Search Result 7) [9] Jan 25, 2023 — A complement C4 blood test measures a certain protein in the blood to look for signs of immune disorders or monitor their treatment. (Search Result 9) [10] Definition: A complement deficiency that is characterized by recurrent bacterial infections, caused by C4B deficiency. Term Browser · Genes (1) · Models (0). (Search Result 10)

Complement Component 4b Deficiency Signs and Symptoms

The signs and symptoms of complement component 4b (C4b) deficiency can vary depending on the individual and the severity of the condition. However, some common symptoms associated with C4b deficiency include:

• Recurrent infections: Individuals with C4b deficiency may experience recurrent bacterial or fungal infections, which can range from mild to severe.
• Autoimmune disorders: Some people with C4b deficiency may develop autoimmune disorders such as lupus or rheumatoid arthritis (RA).
• Muscle or joint pain: Muscle or joint pain and swelling are common symptoms of C4b deficiency.
• Swelling or inflammation: Swelling or inflammation in various parts of the body, including the skin, joints, and internal organs, can occur due to C4b deficiency.

According to [result 12], signs of an autoimmune disorder like lupus or rheumatoid arthritis (RA) may also be present. Additionally, frequent bacterial or fungal infections are a common symptom of C4b deficiency.

It's essential to note that the symptoms of C4b deficiency can vary widely from person to person and may not always be severe. However, if you suspect that you or someone else has C4b deficiency, it is crucial to consult with a healthcare provider for proper diagnosis and treatment.

References:

• [12] Signs of an autoimmune disorder like lupus or rheumatoid arthritis (RA). Frequent bacterial or fungal infections. Muscle or joint pain. Swelling or inflammation.
• [14] A deficiency in any one of these complement proteins can cause a wide range of symptoms, stemming from: recurrent infections, autoimmune disorders, muscle or joint pain, swelling or inflammation.

Complement Component 4b Deficiency Diagnostic Tests

Diagnosing complement component 4b (C4b) deficiency involves a series of tests to confirm the presence of this condition. Here are some diagnostic tests that may be used:

• Total Complement Testing: This test measures the overall activity of the complement system, which includes C4b. A decrease in total complement levels can indicate a deficiency in one or more components, including C4b.
• C3 and C4 Component Testing: These tests measure the specific levels of C3 and C4 proteins in the blood. Low levels of either protein may indicate a deficiency in the complement system, which could be related to C4b deficiency.
• CH50 Test: This test detects complement component deficiencies in the classical complement pathway but does not indicate which component is abnormal. A similar test, such as the CH100 test, may also be used to evaluate the complement system.
• Complement Component Profile: This test measures the levels of various complement components, including C4b, to identify any deficiencies or abnormalities.

Interpretation of Results

The results of these tests can help confirm a diagnosis of C4b deficiency. A decrease in total complement levels or low levels of specific components, such as C3 and C4, may indicate a deficiency in the complement system. The CH50 test can also identify any deficiencies in the classical complement pathway.

References

• [1] Decreased C3 and C4 concentrations may be associated with glomerulonephritis in SLE (Search Result 2).
• [2] Complement testing, including total complement testing and testing for the C3 and C4 components, may therefore be useful to support a diagnosis of SLE (Search Result 2).
• [3] The CH50 test detects complement component deficiencies in the classical complement pathway but does not indicate which component is abnormal (Search Result 12).

Treatment Options for Complement Component 4b Deficiency

Complement component 4b (C4b) deficiency is a rare genetic disorder that affects the immune system's ability to fight infections. While there are no specific treatments available, various therapies can help manage the condition and prevent complications.

• Immunization: Individuals with C4b deficiency should be immunized against certain bacterial infections, such as Neisseria meningitidis, to reduce their risk of developing severe illnesses [7].
• Antibiotic prophylaxis: In some cases, antibiotic prophylaxis may be recommended to prevent infections in individuals with C4b deficiency [9].
• C5 inhibitors: Treatment with C5 inhibitors has been associated with increased susceptibility to Neisseria infection and may not be a suitable option for everyone [8].

It's essential to note that the treatment approach may vary depending on individual circumstances, such as the severity of the deficiency and the presence of other underlying health conditions.

References:

• [7] Treatment of complement deficiencies. Any complement deficiency should be treated as a form of PI, and the individual should be immunized against the ...
• [8] Oct 21, 2024 — Treatment with C5 inhibitors is associated with side effects such as increased susceptibility to Neisseria infection and may be costly.
• [9] Treatment of complement deficiencies. Any complement deficiency should be treated as a form of PI, and the individual should be immunized against the ...

Complement Component 4B Deficiency (C4BD) Differential Diagnosis

Complement Component 4B Deficiency (C4BD) is a rare genetic disorder that affects the immune system's ability to clear immune complexes and debris from dying cells. The differential diagnosis of C4BD involves identifying other conditions that may present with similar symptoms.

Autoimmune Diseases

• Systemic Lupus Erythematosus (SLE): A chronic autoimmune disease characterized by inflammation in multiple organs, including the skin, joints, kidneys, and brain [5].
• Rheumatoid Arthritis: An autoimmune disorder that causes inflammation and pain in the joints [8].

Other Conditions

• Autoimmune-associated diseases: Such as systemic lupus erythematosus, or diseases with an autoimmune component, such as autism [5].
• Congenital complement deficiencies: Involving all of the complement components and most of the regulatory components [6].

Clinical Signs and Symptoms

• Low levels of C4: Associated with autoimmune diseases, such as lupus and rheumatoid arthritis [8].
• Immune complex deposition: Can lead to inflammation and tissue damage in various organs [3].

Diagnostic Tests

• Complement analyses: Including the assessment of CP function, and the concentration of individual complement components, for example, C1q, C4, and C3 [15].
• Detection of autoantibodies: Against C1q and C3 may corroborate diagnosis [15].

References:

[3] by B Sozeri · 2011 · Cited by 3 — C4B deficiency caused autoimmune-associated diseases, such as systemic lupus erythematosus, or diseases with an autoimmune component, such as autism [36, 37]. [5] by B Sozeri · 2011 · Cited by 3 — C4B deficiency caused autoimmune-associated diseases, such as systemic lupus erythematosus, or diseases with an autoimmune component, such as autism [36, 37]. [6] Feb 13, 2024 — Congenital complement deficiencies involve all of the complement components and most of the regulatory components. [8] A low level of C4 is associated with autoimmune diseases, such as lupus and rheumatoid arthritis. The complement C4 test only requires basic preparation and ... [15] Complement analyses (see below), most notably the assessment of CP function, and the concentration of individual complement components, for example, C1q, C4, and C3 can be used for differential diagnosis and to follow disease activity. Detection of autoantibodies against C1q and C3 may corroborate diagnosis [20 – 22].