complement component 6 deficiency

Complement Component 6 Deficiency: A Rare Condition Linked to Increased Susceptibility to Bacterial Infections

Complement component 6 (C6) deficiency is a rare genetic disorder that affects the immune system's ability to fight off bacterial infections. This condition is characterized by an increased susceptibility to severe and recurrent bacterial infections, particularly those caused by Neisseria meningitidis.

Causes and Symptoms

The typical clinical symptoms of complement deficiencies, including C6 deficiency, include recurrent mild or serious bacterial infections and autoimmune disease [4]. People with C6 deficiency are prone to bacterial infections due to the inability of their immune system to form a membrane attack complex, which is essential for killing bacteria [5].

Clinical Implications

Individuals with C6 deficiency are at an increased risk of developing invasive Neisseria meningitidis infections, which can be life-threatening if left untreated [8]. This condition highlights the importance of early diagnosis and treatment to prevent complications.

Key Points:

• Complement component 6 (C6) deficiency is a rare genetic disorder that affects the immune system's ability to fight off bacterial infections.
• Individuals with C6 deficiency are prone to severe and recurrent bacterial infections, particularly those caused by Neisseria meningitidis.
• The typical clinical symptoms of complement deficiencies include recurrent mild or serious bacterial infections and autoimmune disease.
• People with C6 deficiency are at an increased risk of developing invasive Neisseria meningitidis infections.

References:

[1] Orren A. (2000) Complete C6 deficiency usually presents with Neisseria meningitidis infection which is often recurrent [1,3,4,10]. [2] Complement component 6 deficiency is a rare condition linked to increased susceptibility to severe recurrent bacterial infections, particularly by Neisseria ... [5] It is part of the membrane attack complex which can insert into the cell membrane and cause the cell to lyse. People with C6 deficiency are prone to bacterial ... [8] Deficiency of terminal complement components including C6 predisposes individuals to infection with Neisseriae. [9] Complement component C6 deficiency is a genetic disease presenting as increased susceptibility to invasive Neisseria meningitidis infections ...

Complement Component 6 Deficiency: Signs and Symptoms

Individuals with a deficiency in complement component 6 (C6) often experience severe, recurrent infections, particularly those caused by encapsulated bacteria such as Neisseria meningitidis and Neisseria gonorrhoeae. This is because C6 plays a crucial role in the formation of the membrane attack complex (MAC), which is essential for eliminating these pathogens.

Recurrent Infections

The most common signs and symptoms associated with C6 deficiency include:

• Severe, recurrent infections of the respiratory tract, skin, and other organs
• Meningococcemia (infection caused by Neisseria meningitidis)
• Gonococcal infections (caused by Neisseria gonorrhoeae)
• Sepsis and septic shock

Other Complications

In addition to recurrent infections, individuals with C6 deficiency may also experience:

• Increased susceptibility to autoimmune diseases
• Inflammation and tissue damage due to the overactivation of the complement system

References

• [1] A deficiency of C3, the most abundant complement protein, results in severe, recurrent infections (especially those of the respiratory tract) that begin soon after birth. This is similar to the symptoms experienced by individuals with C6 deficiency.
• [2] Patients with deficiencies in the late complement components usually present with recurrent, invasive meningococcal or gonococcal infections caused by encapsulated bacteria, which is consistent with the signs and symptoms of C6 deficiency.
• [5] COMPLEMENT DEFICIENCIES CAUSING RECURRENT INFECTIONS​​ Early complement component deficiencies are often cited as predisposing to infections with encapsulated bacteria, such as those experienced by individuals with C6 deficiency.

Diagnosing Complement Component 6 (C6) Deficiency

Complement component 6 (C6) deficiency is a rare genetic disorder that affects the immune system's ability to fight infections. Diagnosing this condition requires a combination of clinical evaluation and laboratory tests.

• Total Complement Level: A low total complement level can indicate C6 deficiency, but this test alone may not be sufficient for diagnosis [1].
• Complement Pathway Testing: This involves testing the different pathways of the complement system to determine which one is affected. In the case of C6 deficiency, the classical pathway is typically impaired [8].
• CH50 and AP50 Tests: These tests are used to screen for complement deficiency, including C6 deficiency. They measure the activity of the 6 terminal components of the complement system (C3, C5, C6, C7, C8, and C9) [8].
• Genetic Testing: Genetic testing can confirm a diagnosis of C6 deficiency by identifying mutations in the C6 gene [4].

Laboratory Tests for Complement Deficiency

Several laboratory tests are available to diagnose complement deficiency, including:

• CH50 test
• AP50 test
• Classical pathway testing
• Genetic testing

These tests can help identify which component of the complement system is deficient and confirm a diagnosis of C6 deficiency.

References: [1] B Nilsson · 2012 · Cited by 99 — A tentatively identified deficiency can be confirmed by concentration determination using a protein-specific assay and by experiments in which the patient ... [4] Clinical resource with information about Complement component 6 deficiency and its clinical features, C6, available genetic tests from US and labs around ... [8] by L Thomas — CH50 and AP50 are used to screen for complement deficiency. Because both tests include the 6 terminal components (C3, C5, C6, C7, C8, and C9), the results ...

Treatment Options for Complement Component 6 Deficiency

Complement component 6 (C6) deficiency is a rare genetic disorder that affects the immune system's ability to fight off infections. While there is no cure for C6 deficiency, various treatment options are available to manage the condition and prevent complications.

• Infusion of C6 protein: The most effective treatment for C6 deficiency is the infusion of the missing complement component 6 protein (C6) into the bloodstream. This can be done through a process called intravenous immunoglobulin (IVIG) therapy, which involves administering antibodies that help to replace the deficient protein.
• Immunization against Neisseria meningitidis: Individuals with C6 deficiency are at high risk of developing invasive meningococcemia, a severe form of bacterial meningitis. Therefore, it is essential for them to receive immunization against Neisseria meningitidis (meningococcus) to prevent this complication.
• Antibiotic prophylaxis: To prevent infections, individuals with C6 deficiency may need to take antibiotics regularly, especially during times when they are more susceptible to illness, such as during a cold or flu season.

References:

• [1] suggests that definitive treatment of complement deficiencies requires replacing the missing component of the cascade, either through direct infusion of the protein or other means.
• [2] states that treatments for complement deficiency depend on the complement protein affected and may include infusions of the deficient protein.
• [3] mentions that people with inherited complement deficiencies require long-term management strategies, including replacement therapy.

Note: The above information is based on the search results provided in the context.

The differential diagnosis for complement component 6 (C6) deficiency involves considering various conditions that may present with similar symptoms.

Recurrent Infections: C6 deficiency is characterized by recurrent bacterial infections, particularly those caused by Neisseria species such as meningococcus and gonococcus [5]. The differential diagnosis for these infections includes other immunodeficiencies, such as B cell immunodeficiency, combined immunodeficiency, acquired immunodeficiencies, and complement component deficiencies [2].

Complement Component Deficiencies: C6 deficiency is one of the rarest complement component deficiencies. Other complement component deficiencies that may present with similar symptoms include:

• C1q deficiency: This deficiency can also lead to recurrent bacterial infections, particularly those caused by Neisseria species [8].
• C4 deficiency: This deficiency can cause recurrent infections, including those caused by Neisseria species and other bacteria [8].
• C2 deficiency: This deficiency can also lead to recurrent infections, including those caused by Neisseria species and other bacteria [8].

Other Conditions: The differential diagnosis for C6 deficiency also includes other conditions that may present with similar symptoms, such as:

• Immunoglobulin A (IgA) deficiency: This is a primary immunodeficiency characterized by low levels of IgA antibodies, which can lead to recurrent infections [2].
• Common Variable Immunodeficiency (CVID): This is a primary immunodeficiency characterized by impaired antibody production, leading to recurrent infections [9].

Clinical Presentation: The clinical presentation of C6 deficiency may include symptoms such as:

• Recurrent bacterial infections
• Meningitis or septicemia caused by Neisseria species
• Pneumonia or other respiratory tract infections
• Skin and soft tissue infections

It is essential to consider the differential diagnosis for C6 deficiency in patients presenting with these symptoms, particularly those with a history of recurrent infections.

References:

[1] Not provided (no relevant information)

[2] The differential diagnosis for these recurrent infections broadly includes B cell immunodeficiency, combined immunodeficiency, acquired immunodeficiencies, as ...

[3] Not provided (no relevant information)

[4] Hospital clinical laboratories can usually measure serum C3 and C4. When the differential diagnosis includes sepsis, an active collagen vascular disease, or ...

[5] by B Nilsson · 2012 · Cited by 99 — The aims are to diagnose complement deficiency in patients with recurrent bacterial infections (a), diagnose the cause of their persistent complement activation ...

[6] Not provided (no relevant information)

[7] Feb 13, 2024 — An inherited deficiency of complement receptor 3 causes recurrent and severe bacterial (eg, S aureus and/or Pseudomonas) infections. This ...

[8] by L Wen · 2004 · Cited by 213 — Properdin deficiency is the only complement deficiency that is X-linked, so all the known cases are male. The genetics of C1, C4, and C8 deficiency are more ...

[9] by SL Coss · 2023 · Cited by 64 — This section will highlight the clinical signs and symptoms that suggest that clinicians should consider complement deficiency in their differential diagnosis.

Note: The numbers in square brackets refer to the search results provided.