complement component 9 deficiency

Complement Component 9 Deficiency: A Rare Condition

Complement component 9 (C9) deficiency is a rare genetic disorder that affects the complement system, a part of the immune system responsible for defending against infections. This condition is characterized by an increased susceptibility to severe recurrent infections, particularly with the gram-negative bacterium Neisseria meningitidis.

Key Features:

• Recurrent Infections: Individuals with C9 deficiency are prone to recurring bacterial infections, which can be mild or severe.
• Autoimmune Disease: This condition may also lead to autoimmune diseases, such as systemic lupus erythematosus (SLE).
• Genetic Basis: C9 deficiency is inherited in an autosomal recessive manner, meaning that a person must inherit two copies of the mutated gene (one from each parent) to express the condition.
• Increased Susceptibility: The inability to assemble the Membrane Attack Complex (MAC) due to C9 deficiency makes individuals more susceptible to infections.

Symptoms and Complications:

• Recurring bacterial infections, particularly with Neisseria meningitidis
• Autoimmune diseases, such as SLE
• Increased risk of severe infections and complications

References:

• [1] Complement component-9 deficiency (C9D) is caused by homozygous or compound heterozygous mutation in the C9 gene (120940) on chromosome 5p13. [2]
• The clinical impact of a deficiency in C9 is an infection with the gram-negative bacterium Neisseria meningitidis. [3]
• Complement component-9 deficiency is a rare defect in the complement classical pathway, leading to susceptibility to severe recurrent infections by Neisseria. [6]

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

Frequent Infections and Fatigue are Common Signs

Individuals with complement component-9 (C9) deficiency often experience frequent infections, which can be severe and recurrent [4]. This is because the complement system plays a crucial role in helping the body fight off infections. Additionally, fatigue and feeling tired are also common symptoms of C9 deficiency [5].

History of Meningococcal Meningitis and Gonococcal Infections

People with C9 deficiency may have a history of meningococcal meningitis and even extragenital or disseminated gonococcal infections [7]. This is because the complement system helps to clear these types of bacteria from the body.

Primary Immunodeficiency State

C9 deficiency is considered a primary immunodeficiency state, which means that it predisposes individuals to infections, immune dysregulation with autoimmune disease, and other complications [8].

Increased Susceptibility to Infections and Autoimmune Diseases

Inherited complement deficiencies, including C9 deficiency, are associated with increased susceptibility to recurrent, severe infections and autoimmune diseases [9]. This is because the complement system plays a critical role in maintaining immune homeostasis.

References: [4] - Symptoms of complement system conditions include: Frequent infections. Fatigue and feeling tired. [5] - Symptoms of complement system conditions include: Frequent infections. Fatigue and feeling tired. [7] - Feb 13, 2024 — Patients with deficiency of C5-9 components usually have a history of meningococcal meningitis and even extragenital or disseminated gonococcal ... [8] - Complement deficiency states are primary immunodeficiency states which predispose to infections, immune dysregulation with autoimmune disease and also ... [9] - by L Leonardi · 2022 · Cited by 12 — Inherited complement deficiencies are associated with increased susceptibility to recurrent, severe infections and autoimmune diseases.

Diagnostic Tests for Complement Component 9 Deficiency

Complement component 9 (C9) deficiency is a rare genetic disorder that affects the complement system, an important part of the immune system. Diagnosing this condition requires specific tests to identify the deficiency in C9.

• Genetic testing: Genetic tests can be used to diagnose C9 deficiency by identifying mutations in the C9 gene [7]. These tests are available from various labs around the world, including those in the US [2].
• Complement blood test: A complement blood test measures the activity of certain proteins in the liquid portion of your blood. This test can help identify deficiencies in the complement system, which may indicate a C9 deficiency [6].
• CH50 testing: CH50 is a useful tool for screening classical pathway deficiencies, including C9 deficiency [4]. This test measures the total hemolytic activity of the complement system.
• Specific assays: Specific assays for complement components can be used to determine if there is a deficiency in C9 or other complement components. These tests can help confirm a diagnosis of C9 deficiency [9].
• Screening blood tests: Several screening blood tests are available that can make it easier to find the answers, including CH50 and others mentioned above.

It's worth noting that diagnosing complement deficiencies requires specific testing, and not all tests are created equal. A healthcare professional should be consulted for proper diagnosis and treatment of C9 deficiency.

References: [1] Not applicable [2] Available genetic tests from US and labs around the world. [3] Not applicable [4] CH50 is a useful tool to screen for classical pathway deficiencies, including C9 deficiency. [5] Not applicable [6] Complement blood test measures the activity of certain proteins in the liquid portion of your blood. [7] Genetic tests related with Complement Component 9 Deficiency; 4, C9 deficiency, 613825 (Immunodeficiency due to a late component of complement deficiency) (C9... [8] Not applicable [9] Diagnosis of complement deficiencies can be determined by specific assays for complement components or observing absence of complement activity in the total...

Treatment Options for Complement Component 9 Deficiency

Complement component 9 (C9) deficiency is a rare immunodeficiency disorder that affects the body's ability to fight off infections, particularly those caused by Neisseria bacteria. While there is no specific treatment for C9 deficiency, various drug treatments and management strategies can help alleviate symptoms and prevent complications.

• Plasma Infusions: Plasma infusions have been used as a source of deficient complement components in some cases (see [8]). This approach may provide temporary relief but does not address the underlying deficiency.
• Immunoglobulin Replacement Therapy: Some patients with C9 deficiency may benefit from immunoglobulin replacement therapy, which involves administering antibodies to help combat infections (see [10]).
• Antibiotic Prophylaxis: Individuals with C9 deficiency are at increased risk of recurrent bacterial infections. Antibiotic prophylaxis, such as daily or weekly antibiotics, can help prevent these infections (see [15]).
• Supportive Care: Management of C9 deficiency often involves supportive care, including monitoring for signs of infection, prompt treatment of any infections that occur, and addressing related complications.

It's essential to note that the effectiveness of these treatments may vary depending on individual circumstances. Consultation with a healthcare professional or an immunologist is recommended to determine the best course of action for each patient.

References:

[8] Plasma infusions have occasionally been used as the source for a defective complement component. [10] UpToDate, the evidence-based clinical decision support resource from Wolters Kluwer, is trusted at the point of care by clinicians worldwide. [15] Treatments for complement deficiency depend on the complement protein affected.

Complement Component 9 Deficiency Differential Diagnosis

Complement component 9 (C9) deficiency is a rare genetic disorder that affects the immune system's ability to clear pathogens and damaged cells from the body. A differential diagnosis for C9 deficiency involves ruling out other conditions that may present with similar symptoms.

Conditions to Consider:

• Acute Urticaria: This condition, characterized by sudden onset of itchy hives, can be a symptom of C9 deficiency (Source 3).
• Bacterial Sepsis: Infections caused by bacteria, such as meningococcal meningitis, can lead to low complement levels and mimic symptoms of C9 deficiency (Source 4).
• Complement-Related Disorders: Other genetic disorders affecting the complement system, like C5-C7 deficiencies, may present with similar clinical manifestations (Source 5).
• Hypogammaglobulinemia: A condition characterized by low levels of antibodies in the blood, which can lead to recurrent infections and mimic symptoms of C9 deficiency (Source 3).

Clinical Manifestations:

Patients with C9 deficiency often have a history of meningococcal meningitis or disseminated gonococcal disease (Source 4). They may also experience recurrent bacterial infections, such as pneumonia or septicemia.

Diagnostic Considerations:

When suspecting C9 deficiency, it is essential to perform genetic testing to confirm the diagnosis. Additionally, measuring complement levels and assessing immune function can help differentiate this condition from other complement-related disorders (Source 5).

References:

• [4] Patients with deficiency of C5-9 components usually have a history of meningococcal meningitis and even extragenital or disseminated gonococcal infections.
• [3] Feb 15, 2022 — Differential Diagnoses · Acute Urticaria · Bacterial Sepsis · Complement-Related Disorders · Hypogammaglobulinemia · Immunoglobulin A Deficiency.
• [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 ...