### WDR5 Gene Overview

- **Gene Symbol**: WDR5
- **Location**: The WDR5 gene is located on human chromosome 4q21.23.
- **Function**: As a member of the WD repeat protein family, WDR5 plays a critical role in various cellular processes, particularly in chromatin modification and gene regulation. It is best known for its involvement in histone methylation, where it contributes to the trimethylation of histone H3 at lysine 4 (H3K4me3), a modification that is often associated with active gene transcription.

### Additional Associated Genes

While the summaries provided mention several genes involved in histone modification (e.g., KMT2A, KMT2B, KMT2C, KMT2D, SETD1A, SETD1B), WDR5 is also known to interact with:

- **RBBP5**: Partner in histone methyltransferase activity.
- **ASH2L**: Works alongside WDR5 to stimulate methyltransferase activity.
- **MLL1/MLL Complex**: In facilitating methylation of histone marks.
- **NSL Complex**: Associated with histone acetylation regulation.
  
Additional studies also suggest possible interactions with transcription factors like MYC and involvement with regulatory proteins such as INO80, which is implicated in chromatin remodeling.

### Age-Related Disease Associations

WDR5 has been implicated in:

- **Cancer**: Aberrant regulation of histone methylation by WDR5 has been noted in various cancers, including leukemia. Its interaction with MLL fusion proteins has been particularly associated with the pathology of acute leukemias.
- **Neurodegenerative Diseases**: There may be connections between WDR5 activity and age-related neurodegenerative conditions, though current research is primarily focused on histone modifications in cellular aging and senescence mechanisms.

### Drug Interactions

Currently, there are no specific drugs that are recognized to directly target WDR5; however, the following classes may indirectly affect its function:

- **Histone Methyltransferase Inhibitors**: Since WDR5 is a component of histone methyltransferase complexes, compounds like small-molecule inhibitors targeting settings of KMT2 family enzymes may influence WDR5's activity.
- **Epigenetic Modifiers**: Drugs influencing chromatin structure (like HDAC inhibitors) could affect pathways involving WDR5 through broader changes in histone modifications.

### Pathways and Biological Processes

WDR5 is involved in several key biological pathways:

- **Histone Methylation Pathway**: Notably in the methylation of histone H3 at lysine 4 (H3K4me3), which is critical for transcriptional activation.
- **Regulation of Gene Expression**: Participates in transcriptional regulation by modifying chromatin structure.
- **Signal Transduction and Cellular Processes**: Plays roles in cell cycle regulation, apoptosis, and developmental processes.
- **Stem Cell Regulation**: WDR5 is involved in stem cell maintenance and differentiation processes.

In summary, WDR5 serves as a crucial mediator of histone methylation and transcription regulation, with implications in cancer biology and potential connections to aging and neurodegenerative diseases. It interacts with a variety of proteins involved in these processes and participates in complex regulatory networks influencing gene expression.