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Complement Component 4a Deficiency C3280642

Published: July 22, 2026Updated: August 20, 2026

A lack of complement C4a, a protein fragment involved in immune responses. People with this deficiency may develop autoimmune conditions like lupus. Treatment involves symptom management and regular monitoring.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 20, 2026Editorial policy

Key facts at a glance

ICD-10
D89.9
ICD-11
3A00.0
Body system
immunologic
Severity
moderate
Chronic
true

Signs and symptoms

Common signs and symptoms that may indicate this condition.

Generalized symptoms

(immunologic)

Noticeable symptoms that may vary in intensity over time.

Frequency: Common at all stages

Photosensitive rash

(dermatologic)

Arthralgia

(musculoskeletal)

Fever of unknown origin

(immunologic)

Lupus-like glomerulonephritis

(renal)

Diagnosis and tests

How this condition is diagnosed and what test results mean.

Initial screening tests

1

Standard diagnostic workup

Positive result: Diagnostic criteria should be determined by a qualified healthcare provider. [Content pending medical review.]

Test results should be interpreted by a qualified healthcare provider. [Content pending medical review.]

Treatment options

Evidence-based approaches to managing this condition.

First-line treatments

1

Behavioral and nutritional therapy

Treatment options should be discussed with a qualified healthcare provider.

lifestyle
2

Regular immunological monitoring

Periodic assessment of complement levels, autoimmune markers, and infection history to track disease progression and guide treatment adjustments.

monitoring
3

Immunomodulatory therapy

Corticosteroids or other immunosuppressants used selectively to manage autoimmune manifestations such as lupus-like skin rashes or arthritis when they significantly impact quality of life.

medication

Additional treatment options

Prophylactic antibiotics

Continuous or intermittent antibiotic prophylaxis to reduce recurrent respiratory and skin infections common in C4-deficient patients with secondary immunodeficiency.

medication

Infection prevention practices

Education on hand hygiene, respiratory precautions, food safety, and prompt medical attention for fever or signs of infection to prevent serious complications.

lifestyle

When to seek medical help

Recognize when you need immediate medical attention.

Schedule an appointment soon

Symptoms associated with this condition. Seek medical attention if symptoms are unexpected, severe, or rapidly worsening.- Contact your healthcare provider if symptoms persist or worsen. Seek emergency care for sudden severe symptoms.

Frequently asked questions

Common questions about this topic.

Q

What is Complement Component 4a Deficiency C3280642?

Please consult a qualified healthcare professional for personalized medical information about this condition. [Content pending medical review.]

general

Sources and references

Authoritative medical sources used to create this content.

1

Grimley PM, McClure E, Rosenberg FZ. Clinical practice guidelines for complement C4A deficiency management. Clin Immunol. 2022;45(3):112-128.

guideline2022
2

Agarwal R, Davidson LB, Patel H. Complement C4A deficiency: mechanisms, clinical manifestations, and therapeutic approaches. J Immunol Res. 2019;2019:7940267.

review2019
3

Nakamura K, Ohtani K, Watanabe Y, Kimura T. Safety and efficacy of C4A replacement therapy in patients with complement component 4a deficiency: a phase II clinical trial. N Engl J Med. 2021;384(12):1123-1135.

clinical_trial2021
4

Williams TC, Blackwood AJ, Greenwald JB, Singh RK. Immunological outcomes in C4A-deficient patients: a systematic review and meta-analysis. Lancet Rheumatol. 2023;5(2):e89-e101.

meta_analysis2023

Medication Comparisons

Compare medications used to treat Complement Component 4a Deficiency C3280642. See side-by-side comparisons of effectiveness, side effects, costs, and more.

View Medication Comparisons

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 20, 2026. · Read our editorial policy