Mannose-binding lectin (MBL) deficiency is a condition that affects the immune system. It is a fairly common condition, affecting approximately 5–30 people in every 100. People with this condition have low levels of an immune system protein called mannose-binding lectin in their blood.
People with MBL deficiency may be prone to recurrent infections, including infections of the upper respiratory tract and other body systems. Sometimes those affected may also contract more serious infections, such as pneumonia and meningitis. The exact symptoms caused by infections vary in frequency and severity, depending on the type of infection.
Infants and young children with MBL deficiency seem to be more susceptible to infections, but adults can also develop recurrent infections. In addition, affected individuals undergoing chemotherapy or taking drugs that suppress the immune systems are especially prone to infections.
The treatment of health problems associated with MBL deficiency depends on the severity of the symptoms, but most people do not require any specific treatment. Breakthrough infections are treated with antibiotics as and when they occur. For more severe infections, regular, low-dose prophylactic antibiotics may be prescribed. The quality of life for those affected is good if infections are mild and/or treated promptly.