X-Linked Agammaglobulinemia (XLA) is an inherited immune system disorder in which the body is unable to produce the antibodies necessary to protect against bacteria and viruses.
Also known as Bruton’s Agammaglobulinemia, XLA is caused by a genetic mistake in a gene called Bruton’s Tyrosine Kinase (BTK). This prevents the cells responsible for making antibodies (B cells) from developing normally. The immune system relies on antibodies to fight off infection.
The most common types of bacteria causing infection in patients with XLA are Streptococcus, Staphylococcus and Haemophilus.
XLA Symptoms & Diagnosis
XLA usually becomes apparent in infancy due to recurrent and severe bacterial infections including:
- Ear infections
- Sinus infections
- Diarrhea due to a parasite called Giardia
During a baby’s first few months of life, it is protected from infection by IgG antibodies that are passed through the placenta from the mother. This maternal IgG only lasts for about 6 months, at which time the infant needs to start producing antibodies on its own. Infants with XLA are unable to do this, and therefore become susceptible to these recurrent infections.
XLA can be detected through screening tests that measure both immunoglobulin levels and the number of B cells in the blood.
XLA Treatment & Management
Although there is no cure for XLA, it can be successfully treated. Immunoglobulin replacement therapy is a life-saving, life-long treatment that replenishes some of the missing antibodies. In addition, some people benefit from taking daily oral antibiotics to prevent or treat infections.
Most people with XLA who receive replacement immunoglobulin on a regular basis can lead relatively normal lives.
People with XLA should not receive live viral vaccines, such as those for polio, measles, mumps or rubella. Because XLA results in defective immunity, these vaccines can infect the recipient with the very disease they were intended to prevent. This is true for most immune defects involving B and T cells.
To learn more about XLA and other PIDDs, visit the Immune Deficiency Foundation website.