The gene symbol **MTND3P20** refers to a pseudogene located in the mitochondrial DNA, specifically related to the ND3 subunit of Complex I in the mitochondrial electron transport chain. Here’s an expanded overview based on your request:

### 1. Associated Genes
While MTND3P20 is primarily regarded as a pseudogene and does not encode a functional protein, it is generally associated with the following genes:
- **MT-ND3**: The gene directly encoding the ND3 subunit of NADH dehydrogenase (Complex I). These two may share some sequence homology.
- Other mitochondrial genes involved in oxidative phosphorylation and ATP production may also be indirectly associated with this pseudogene due to their roles in mitochondrial function.

### 2. Aging and Age-related Diseases
- **Mitochondrial Dysfunction**: Though MTND3P20 does not encode for a functional protein, the expression of mitochondrial genes including MT-ND3 may be influenced by age-related mitochondrial dysfunction.
- **Neurodegenerative Diseases**: Alterations in mitochondrial gene function and regulation can be linked to neurodegenerative conditions such as Alzheimer's disease. Since MTND3P20 is associated with ND3, its location suggests potential involvement in pathways that could contribute to energy decline in aging neurons.
- **Metabolic Disorders**: Mitochondrial dysfunction has also been implicated in metabolic syndromes that become more prevalent with aging.

### 3. Drug Interactions
As MTND3P20 is a pseudogene, there are currently no known specific drugs or drug classes that directly interact with it. However, drugs targeting mitochondrial function, such as those used in the management of mitochondrial diseases, might indirectly influence the regulation or expression patterns of mitochondrial-related pseudogenes and functional counterparts.

### 4. Pathways and Biological Processes
- **Mitochondrial Electron Transport Chain**: The closest association of MTND3P20 lies with the mitochondrial electron transport chain, particularly with Complex I function. Although MTND3P20 itself may not participate in these processes, its association implies relevance in pathways tied to energy metabolism.
- **Oxidative Phosphorylation**: Since it is related to ND3, contributions to pathways associated with ATP production through oxidative phosphorylation may be inferred.
- **Regulation of Mitochondrial Gene Expression**: Pseudogenes can exhibit regulatory functions, potentially affecting the expression of associated genes through mechanisms like RNA interference or competition for transcriptional factors.

### Conclusion
For researchers interested in mitochondrial genetics, MTND3P20 serves as an important genomic element, reflecting evolutionary history and potential regulatory implications despite its non-coding nature. The exact roles and interactions require further study to clarify its functional relevance and any implications for aging and disease processes.