### 1. Associated Genes
The CDC73 gene is associated with various other genes, particularly those involved in key cellular processes and signaling pathways:

- **CCND1 (Cyclin D1)**: Critical for cell cycle regulation.
- **KMT2A (MLL1)**: A histone methyltransferase implicated in leukemogenesis and embryonic development.
- **TP53 (p53)**: A tumor suppressor gene involved in cell cycle regulation and apoptosis.
- **CSTF1 (Cleavage Stimulation Factor Subunit 1)**: Involved in the regulation of mRNA polyadenylation.
- **CDKN1A (p21)**: A cyclin-dependent kinase inhibitor implicated in cell cycle regulation.
  
These interactions indicate a broad network of regulatory mechanisms involving CDC73.

### 2. Aging and Age-Related Diseases
While not exclusively linked to aging, CDC73 mutations can lead to conditions such as hyperparathyroidism, which is more prevalent in older adults. Additionally, as a tumor suppressor gene, CDC73 may play a role in age-related cancers, given its association with parathyroid carcinoma. The dysregulation of CDC73 could contribute to the tumorigenesis seen in cancers often found in the aging population.

Recent studies have suggested that dysfunction in transcriptional regulatory mechanisms, including pathways involving CDC73, can lead to age-related declines in cellular function and increased susceptibility to cancer, though direct links may still be an area of ongoing research.

### 3. Drug Interactions
Currently, there are no specific drugs that are universally documented to interact directly with the CDC73 gene. However, drugs targeting downstream effectors involved in the signaling pathways and biological processes associated with CDC73, such as histone deacetylase inhibitors (HDACi) or drugs affecting the Wnt signaling pathway, could indirectly influence expression and activity of pathways modulated by CDC73.

Examples of drug classes:
- **Histone deacetylase inhibitors (HDACis)**: Potentially influence epigenetic regulation associated with tumor suppressor genes.
- **Parathyroid hormone-related drugs**: These may not directly affect CDC73 but are relevant in managing conditions associated with hyperparathyroidism.

### 4. Pathways and Biological Processes
CDC73 is involved in several crucial pathways and biological processes including:

- **RNA Polymerase II Transcription**: Participates in the elongation phase and recruitment of transcriptional machinery.
- **mRNA Processing**: Particularly in 3' mRNA processing and polyadenylation.
- **Wnt Signaling Pathway**: Involvement suggests a role in differentiation and development.
- **Cell Cycle Regulation**: Particularly in regulating the expression of cyclins such as Cyclin D1, which is critical for progression through the cell cycle.
- **Histone Modifications**: Involved in the ubiquitination of histone H2B and methylation of histone H3, linking it to chromatin remodeling and transcriptional regulation.

In sum, CDC73 is a critical gene involved in transcription regulation, tumor suppression, and cellular signaling, with implications for diseases related to aging and cancer.