During which age range do symptoms of Bruton's agammaglobulinemia typically manifest?

Bruton's agammaglobulinemia, also known as X-linked agammaglobulinemia, is a primary immunodeficiency disorder characterized by the absence of mature B cells and consequently a severe deficiency of immunoglobulins. Symptoms typically do not manifest at birth because newborns possess maternal antibodies that provide some level of protection. However, as maternal antibody levels diminish, typically around 6 months of age, the child starts to show symptoms related to the immunodeficiency due to the lack of production of their own immunoglobulins.

In the age range following 6 months, children with Bruton's agammaglobulinemia begin to experience recurrent bacterial infections, particularly with encapsulated organisms, as their humoral immune response is greatly impaired. The manifestation of symptoms in this age range of after 6 months is key to the diagnosis of the condition since it aligns with the depletion of maternal immunoglobulins and the child's inability to produce sufficient immunoglobulins on their own. As the child continues to grow, infections may become more frequent and severe, leading to further clinical evaluation and diagnosis.