Complement is a group of more than 30 different proteins that are involved in a biochemical pathway, called the complement pathway. This pathway plays a critical role in inflammation, which serves as a defence against some bacterial and viral infections. The term complement deficiency is used when proteins are missing or do not function properly.
Complement deficiencies are rare and will cause people to have different symptoms depending on which complement protein is affected. Most complement deficiencies have a genetic cause and family members of those affected may need to be tested.
Treatments for complement deficiency depend on the complement protein affected. People who are more susceptible to bacterial infections might need to take daily antibiotics and be vaccinated to improve their protection against specific infections.