X-Linked Agammaglobulinemia (Bruton's)
What is X-Linked Agammaglobulinemia (Bruton's)?
X-Linked Agammaglobulinemia, also known as Bruton's disease or XLA, is a rare genetic disorder that affects the immune system. People with this condition cannot produce enough antibodies, the proteins that help fight off infections. This happens because their bodies lack B cells, a type of white blood cell that normally makes antibodies.
The condition gets its name because the gene mutation is located on the X chromosome. Boys are almost always affected because they have only one X chromosome. Girls can carry the gene mutation but rarely show symptoms because they have a second X chromosome that usually works normally. Without enough antibodies, people with XLA face a much higher risk of repeated bacterial infections.
XLA is present from birth but symptoms often appear in the first few years of life. Early diagnosis through blood testing can help prevent serious complications. With proper treatment, many people with this condition can lead active lives and avoid severe infections.
Symptoms
- Repeated ear infections, sinus infections, or pneumonia starting in infancy or early childhood
- Chronic diarrhea or digestive problems
- Skin infections that keep coming back
- Slow growth or failure to gain weight in infants
- Conjunctivitis or pink eye that occurs frequently
- Meningitis or brain infections
- Joint swelling and pain
- Severe infections from bacteria that healthy immune systems usually handle easily
Most children with XLA develop frequent infections before age 2. Some babies may seem healthy at first because antibodies from their mother provide temporary protection. Symptoms typically become noticeable once this maternal protection fades after the first few months of life.
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Causes and risk factors
XLA is caused by mutations in the BTK gene, which provides instructions for making a protein needed for B cell development. This genetic change is inherited in an X-linked pattern. Mothers who carry the mutation on one of their X chromosomes can pass it to their children. Sons who inherit the mutated gene will develop XLA. Daughters who inherit it become carriers but usually remain healthy.
Because the condition is genetic, there are no lifestyle or environmental risk factors that cause it. However, having a family history of XLA or recurrent infections in male relatives increases the likelihood of being a carrier. About one-third of cases occur without any family history due to new mutations. Brothers of affected boys have a 50% chance of also having the condition if their mother is a carrier.
How it's diagnosed
XLA is diagnosed through blood tests that measure immune system components. A complete blood count with lymphocyte analysis can reveal very low or absent B cells. Most people with XLA have B cells that make up less than 2% of their total lymphocytes. Blood tests also measure immunoglobulin levels, which are typically very low or undetectable in all antibody types.
Rite Aid offers testing that includes lymphocyte measurements as part of our flagship panel. This can help identify abnormalities that suggest immune deficiencies. If initial screening shows concerning results, your doctor will likely order genetic testing to confirm the BTK gene mutation. Early diagnosis allows treatment to begin before serious infections develop.
Treatment options
- Immunoglobulin replacement therapy given through IV infusion or subcutaneous injection every 2 to 4 weeks
- Antibiotics to treat bacterial infections quickly when they occur
- Preventive antibiotics in some cases to reduce infection frequency
- Regular monitoring by an immunologist or specialist in immune disorders
- Avoiding live vaccines since the immune system cannot handle them safely
- Good hygiene practices including frequent handwashing
- Dental care to prevent oral infections
- Nutrition support to maintain healthy growth and development
Concerned about X-Linked Agammaglobulinemia (Bruton's)? Get tested at Rite Aid.
- Simple blood draw at your nearest lab
- Results in days, not weeks
- Share results with your doctor
Frequently asked questions
With proper treatment including regular immunoglobulin replacement therapy, most people with XLA can live well into adulthood. Early diagnosis and consistent treatment have greatly improved outcomes over the past few decades. However, life expectancy depends on preventing serious infections and managing complications like chronic lung disease.
There is currently no cure for XLA, but the condition can be managed effectively with lifelong treatment. Immunoglobulin replacement therapy provides the antibodies that the body cannot make on its own. Some research is exploring gene therapy and bone marrow transplants as potential future treatments. For now, consistent therapy allows most people to avoid severe infections.
Most people with XLA receive immunoglobulin therapy every 2 to 4 weeks. The exact frequency depends on individual needs and how the body responds to treatment. Some people receive intravenous infusions at a hospital or clinic. Others use subcutaneous infusions at home, which may be given more frequently but in smaller doses.
Girls very rarely develop XLA because they have two X chromosomes. If one X chromosome carries the mutation, the other usually provides enough normal BTK protein for B cells to develop. Girls can be carriers of the gene mutation and pass it to their children. In extremely rare cases, girls may show some symptoms if the normal X chromosome is not active in enough cells.
Bacterial infections are the main concern in XLA because antibodies primarily fight bacteria. Common infections include ear infections, sinusitis, pneumonia, and skin infections. Bacteria like Streptococcus and Haemophilus influenzae cause most problems. People with XLA can usually fight viral and fungal infections normally because those rely on T cells, which work properly in this condition.
XLA specifically affects B cells and antibody production while T cells function normally. This differs from combined immune deficiencies where both B and T cells are affected. People with XLA have normal or low total lymphocyte counts depending on T cell numbers. The key feature is severely reduced or absent B cells, usually less than 2% of lymphocytes.
Yes, most children with XLA can attend school and daycare with proper precautions. Regular immunoglobulin therapy helps prevent infections and allows normal activities. However, they should avoid contact with people who have active infections when possible. Parents should inform teachers and caregivers about the condition and the need for good hygiene practices.
Undiagnosed XLA can lead to repeated severe infections that damage organs over time. Chronic lung infections may cause permanent lung damage called bronchiectasis. Repeated infections can also affect joints, the digestive system, and overall growth. Early diagnosis and treatment prevent most of these complications by stopping infections before they cause lasting harm.
Yes, genetic counseling and testing are recommended for family members. Mothers of affected boys should get carrier testing to understand risks for future pregnancies. Sisters of affected boys may also want testing to know their carrier status. Brothers should be tested even if they seem healthy, since early treatment improves outcomes significantly.
People with XLA can receive most killed or inactivated vaccines, though they may not produce a strong immune response without B cells. They should never receive live vaccines like MMV, oral polio, or live flu vaccine because their immune system cannot control even weakened viruses. Family members should stay up to date on vaccinations to protect the person with XLA from infections.