The SYNJ2-IT1 gene, also referenced as a long non-coding RNA (lncRNA), is located at chromosome 21. It is categorized as an antisense transcript of the SYNJ2 gene, which encodes a protein involved in clathrin-mediated endocytosis and synaptic function. Although it is primarily non-coding, it has been implicated in regulatory roles in cellular processes. Below is a detailed overview based on your requests:

### 1. Associated Genes
While the summaries from NCBI and UniProt may not specifically enumerate associated genes, various studies have suggested potential interactions and associations with several other genes involved in cellular signaling, neuronal development, or synaptic functions. Some of these include:
- **SYNJ2**: As the gene's direct counterpart, it is involved in synaptic vesicle recycling.
- **SYN2**: Another synapse-related gene.
- **AP2A1**: Encoding a component of the adaptor complex required for endocytosis.
- **HSPG2**: Involved in extracellular matrix organization and synaptic structure.

### 2. Aging and Age-Related Diseases
While direct research specifically linking the SYNJ2-IT1 gene to aging or age-related diseases may still be under exploration, the following points are relevant:
- **Neurodegenerative Diseases**: lncRNAs like SYNJ2-IT1, through their role in synaptic function and cellular signaling, may play a part in neurodegenerative processes impacted by aging, such as Alzheimer’s Disease.
- **Cellular Aging**: Alterations in lncRNA expression, including those like SYNJ2-IT1, have been observed with age, suggesting potential roles in cellular senescence and stress responses.

### 3. Drug Interactions
Currently, specific drugs targeting the SYNJ2-IT1 gene directly may not be widely documented in the literature. However, as lncRNAs can influence gene expression, therapeutic strategies targeting associated pathways, such as:
- **Antisense Oligonucleotides**: Designed to modulate lncRNA function.
- **Small Molecule Inhibitors**: Targeting regulatory networks where lncRNAs participate might indirectly influence SYNJ2-IT1 functions.

Some classes of drugs for diseases linked with SYNJ2, such as neurodegenerative disorders, include:
- **Neuroprotective Agents**: Compounds that can offer protective effects on neural pathways potentially affected by SYNJ2-IT1 activity.

### 4. Pathways and Biological Processes
The SYNJ2-IT1 gene has been implicated in various biological pathways and processes, which include:
- **Clathrin-Mediated Endocytosis**: Influencing the dynamics of synaptic vesicles.
- **Regulatory Role in Gene Expression**: Its presence affects the transcriptional regulation of nearby genes.
- **Neurodevelopment**: Participation in neuronal differentiation and maintenance of synaptic function.
  
These processes underscore its potential significance in neuronal function and the impact of dysregulation in conditions such as neurodegeneration.

### Conclusion
The SYNJ2-IT1 gene represents a significant aspect of gene regulation associated with synaptic functions. Ongoing research is crucial for elucidating its precise roles in aging, potential drug interactions, and extensive participation in biological pathways.