Symptoms and diagnosis of MBL deficiency

The symptoms you may recognise and which may have led your doctor to a diagnosis of MBL deficiency are those associated with having recurrent respiratory infections. These usually affect the upper airways and include infections of the throat and ear; the latter causing otitis media.

People with MBL deficiency may sometimes also get more serious infections, such as pneumonia and meningitis.

Common causes of infection in MBL deficiency

Common infections in MBL deficiency are due to viruses, e.g. influenza and bacteria, such as Pseudomonas aeruginosa and Staphylococcus aureus.

Children and MBL deficiency

Infants and young children with MBL deficiency seem to be more susceptible to
infections. This is because the lectin pathway plays an important role in fighting
bacterial infections during the period when the antibody protection from the mother decreases and the child’s own antibody production is not fully working.

How is MBL deficiency diagnosed?

The diagnosis is made using a sample of the patient’s blood. This is tested to see if the MBL protein is present in normal levels or is reduced. If it is reduced, then the patient’s condition is classified as being mild, moderate or severe deficiency, with severe being complete deficiency when there is no detectable MBL in the blood.