Cd40lg, also known as CD40 ligand, is a crucial protein in the immune system. It plays a significant role in the interaction between T cells and B cells, as well as antigen-presenting cells. By binding to CD40, it activates various immune-related pathways, such as costimulatory signals, which are essential for the regulation of humoral and cellular immune responses [3,7].

Mutations in the CD40LG gene are associated with X-linked hyper-IgM syndrome (XHIGM), a primary immunodeficiency disorder. Patients with XHIGM have abnormal levels of immunoglobulins, with decreased IgG and IgA but normal or elevated IgM. They are highly susceptible to infections like pneumonia, diarrhea, and skin ulcers [2,4,6]. Additionally, CD40LG-associated X-linked hyper-IgM syndrome can present with pulmonary alveolar proteinosis [2]. Some patients have also developed anti-phospholipid syndrome, a new complication associated with XHIGM [6]. Computational analysis of CD40LG variants in atypical X-linked hyper-IgM syndrome can help identify the deleterious effects of these variants and potential mechanisms for protein dysfunction [5]. Moreover, CD40LG triplication is associated with immune dysregulation and exhaustion [1]. In the context of Sjögren's disease, a CD40 ligand antagonist, dazodalibep, shows potential as a new therapy, indicating the importance of the CD40/CD40 ligand pathway in its pathogenesis [7].

In conclusion, Cd40lg is essential for proper immune system function. Studies related to its mutations and duplications, as well as the use of its antagonist, have provided insights into various immune-related disorders, including primary immunodeficiencies and autoimmune diseases. Understanding Cd40lg's role helps in developing better diagnostic and therapeutic strategies for these conditions.