The TNFSF13B gene, also known as **A proliferation-inducing ligand** (APRIL), is critical in the regulation of B-cell biology and immunity. Below are additional details regarding TNFSF13B based on your requests:

### 1. Associated Genes:
In addition to the receptors mentioned in the summaries (TNFRSF13B/TACI, TNFRSF17/BCMA, TNFRSF13C/BAFFR), the following genes may be associated or interact with TNFSF13B in various signaling pathways or immune responses:
- **BAFF (TNFSF13)**: This gene encodes another cytokine involved in B-cell survival and differentiation, sharing similar receptor interactions with APRIL (TNFSF13B).
- **CD40**: This gene encodes a costimulatory protein that has implications in B-cell activation and differentiation and may interact indirectly in pathways influenced by APRIL.
- **IκB Kinase**: Components of the NF-κB pathway are indirectly associated with TNFSF13B signaling, as these pathways are crucial for the activation of B cells and other immune responses.

### 2. Aging and Age-Related Diseases:
Recent studies have suggested that dysregulation of TNFSF13B and its associated pathways can be involved in various age-related diseases, particularly:
- **Autoimmune Diseases**: Increased levels of APRIL have been implicated in autoimmune conditions, which can be more common in older adults.
- **Cancer**: The TNF superfamily plays a role in tumorigenesis; aging can enhance chronic inflammation, which may affect APRIL levels and immune regulation.
- **Immunosenescence**: During aging, changes in B-cell responses, including altered responses to APRIL, have been noted, potentially reducing the effectiveness of vaccinations in older populations.

### 3. Drug Interactions:
Several therapeutic interventions may target the pathways involving TNFSF13B:
- **Monoclonal Antibodies**: Drugs such as **belimumab** (a B-cell inhibitor) and **atacicept** (a dual inhibitor of BAFF and APRIL) have been designed to modulate B-cell activity and are being explored for autoimmune diseases like systemic lupus erythematosus (SLE).
- **Small Molecule Modulators**: Targeting the signaling pathways downstream of TNFSF13B could involve other immunomodulatory compounds, although specific classes may not be extensively characterized yet.

### 4. Pathways and Biological Processes:
TNFSF13B is implicated in various biological processes and signaling pathways:
- **B-Cell Activation**: Plays a central role in promoting the proliferation and differentiation of naïve B cells into plasma cells.
- **Humoral Immunity Regulation**: Acts to enhance antibody production through interaction with B-cell receptors.
- **Cytokine Signaling Pathways**: Involvement in NF-κB signaling pathways, leading to prolonged survival signals in B cells.
- **Cell Survival and Differentiation**: Participates in the pathways that dictate cell survival (by promoting mature B-cell survival) and differentiation towards antibody-secreting cells.

Understanding the role of TNFSF13B at the molecular level is critical for developing novel therapeutic strategies targeting immune dysregulation and enhancing B-cell responses in various diseases, especially those impacted by aging.