X-linked agammaglobulinemia (XLA) is an inherited disorder that affects the immune system. Affected individuals are unable to produce enough antibodies, which are the part of the immune system that attaches itself to the invading bacteria and mark them for destruction by the rest of the immune system. Infants are protected for the first few months of life due to the transfer of antibodies from mom to fetus through the placenta. Once the maternal supply has diminished, the infections become more common. The most common illnesses are ear infections, pink eye, pneumonia and sinus infections. Because their immune system is so poor, these can become life-threatening infections. Affected individuals are also more susceptible to infections that cause chronic diarrhea. There is no cure for XLA, however with extreme care during times of illness and regular gammaglobulin treatments, quality of life is improved and life expectancy is near normal for affected individuals. XLA is caused by pathogenic variants in the BTX gene.