X-LINKED AGAMMAGLOBULINEMIA (XLA)
Dr Ira Shah
Consultant Pediatrician, Nanavati Hospital and B.J.Wadia Hospital for Children, Mumbai
Editor - Pediatric Oncall
What is X-linked agammaglobulinemia?
XLA is a primary immunodeficiency in which patients are unable to produce antibodies (immunoglobulins). As a result, these patients are prone to get recurrent bacterial infections. XLA is also called as Bruton's agammaglobulinemia or congenital agammaglobulinemia.
What are the symptoms of X-linked agammaglobulinemia?
Symptoms of XLA are recurrent bacterial infections especially in the ears, sinuses and lungs. They may also get diarrhea, skin infections and serious infections such as septicemia. Common organisms causing infections in these patients are pneumococcus, streptococcus, staphylococcus and hemophilus influenza.
What is the cause of X-linked agammaglobulinemia?
Cause of XLA is a genetic cause. Due to mutations in BTK gene (Bruton's Tyrosine Kinase gene) which is located on X-chromosome, the B-lymphocytes are not formed in patients with XLA. As a result the B-lymphocytes are unable to produce antibodies. Thus, these patients have very small tonsils and lymph nodes as bulk of tonsils and lymph nodes is formed of B-lymphocytes which are absent in these patients. Since the genetic defect is present on the X-chromosome, XLA is seen in boys only.
How is the diagnosis of X-linked agammaglobulinemia made?
Diagnosis of XLA is established by demonstrating decreased IgG, IgA, & IgM immunoglobulins in the blood along with low number of B-lymphocytes. Diagnosis of XLA is confirmed by demonstrating absence of BTK protein in monocytes or platelets or by detection of mutation in BTK gene by genetic tests.
What is the treatment of X-linked agammaglobulinemia?
Treatment of XLA consists of immunoglobulin replacement therapy. Patients with XLA should not receive live vaccines such as oral polio vaccine, MMR vaccine.
What is the inheritance of X-linked agammaglobulinemia?
Inheritance of XLA is due to defect on X-chromosome. Females have no disease but may be carriers of the defective gene. A brother of the affected boy with XLA has 50% chance of having the disease whereas the sisters may be carriers or have no gene defect. If the father is suffering from XLA, then his daughters will be carriers of the defective gene whereas the sons will be normal. Currently these genetic tests are being performed only in few laboratories.
What is the life expectations of patients with X-linked agammaglobulinemia?
Most XLA patients who receive immunoglobulins will be able to lead relatively normal life.
Last updated on 26-3-2011