PAX5-related B lymphopenia and autism spectrum disorder is a condition where a deficiency in the PAX5 gene leads to both immune and neurodevelopmental challenges. People with this condition may experience immune issues because the early development of B cells is affected. These B cells are important for fighting infections and supporting overall immune responses. Additionally, this genetic deficiency is linked to neurodevelopmental abnormalities, including features found in autism spectrum disorder. Autism spectrum disorder can affect social communication and behavior, and its presence in this condition highlights the broader impact of PAX5 deficiency on brain development and function.

People with this condition may experience signs of both immune and developmental challenges. Notably, features of autism spectrum disorder such as difficulties in social interaction and communication might be present. In addition, low levels of immunoglobulins due to impaired B cell development can be associated with increased susceptibility to infections.

The condition is caused by a deficiency in the PAX5 gene. This gene defect affects the early development of B cells in the immune system and is also linked to neurodevelopmental abnormalities. The genetic nature of this condition means that changes in the gene disrupt normal immune function and brain development.