**EHHADH Gene Overview:**
The EHHADH (enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase) gene encodes a bifunctional enzyme that plays a significant role in peroxisomal beta-oxidation of fatty acids. It has two primary enzymatic activities located in different regions of the protein, where the N-terminal region performs enoyl-CoA hydratase activity and the C-terminal region exhibits 3-hydroxyacyl-CoA dehydrogenase activity. This gene is crucial for the breakdown of long-chain fatty acids and branched-chain fatty acids, and its dysfunction is linked to peroxisomal disorders, including Zellweger syndrome.

### 1. Genes Associated with EHHADH:
While the summaries provide information mainly about EHHADH, several other genes can be associated with its function within the realm of fatty acid metabolism and peroxisomal disorders, including:

- **HSD17B4**: Collaborates with EHHADH to catalyze specific reactions involving fatty acid metabolites, crucial for the peroxisomal beta-oxidation process.
- **ACOX1**: Encodes acyl-CoA oxidase, which initiates fatty acid oxidation in peroxisomes.
- **DHA**: Involved in peroxisomal transport processes related to fatty acid metabolism.
- **PEX genes**: Such as PEX1, PEX2, and PEX3, which are vital for peroxisome biogenesis and function, can indirectly relate to EHHADH through peroxisomal disorder phenotypes.

### 2. Aging and Age-Related Diseases:
Research on EHHADH highlights potential associations with aging and age-related diseases. Some details include:

- **Metabolic Syndrome**: Dysfunctional fatty acid metabolism due to impaired EHHADH activity may contribute to metabolic disorders, which are more prevalent with aging.
- **Neurodegenerative Disorders**: Abnormalities in peroxisomal functions, including those involving EHHADH, have been suggested to play a role in neurodegenerative diseases, possibly contributing to age-related cognitive decline.
- **Longevity**: Proper functioning of EHHADH is crucial for maintaining cellular energy levels and lipid homeostasis, which are important for healthy aging and longevity.

### 3. Drug and Drug Classes Interacting with EHHADH:
Currently, there are no specific drugs directly targeting EHHADH listed in databases like DrugBank or clinical literature. However, the following general drug classes may have indirect effects:

- **Peroxisome proliferator-activated receptor (PPAR) agonists**: These are often investigated in the context of lipid metabolism and may influence fatty acid oxidation pathways involving EHHADH.
- **Fatty acid metabolism modulators**: Some statins and other lipid-lowering medications may affect fatty acid metabolism indirectly but do not specifically target EHHADH.

### 4. Pathways and Biological Processes Involved:
EHHADH is involved in several critical biological pathways and processes, including:

- **Fatty Acid Beta-Oxidation Pathway**: Specifically, the peroxisomal beta-oxidation pathway, which is vital for the degradation of very long-chain and branched-chain fatty acids.
- **Lipid Metabolism**: Regulation of lipid catabolism and homeostasis is influenced by EHHADH activities.
- **Peroxisome Metabolism**: Functions as part of the cellular mechanisms crucial for normal peroxisome functioning and biogenesis.
- **Regulation of Medium-Chain Dicarboxylic Acids**: Involvement in the balance and degradation of dicarboxylic acids, which are significant for lipid metabolism regulation.

### Conclusion:
The EHHADH gene plays a critical role in the metabolism of fatty acids, and its proper function is essential for maintaining lipid homeostasis and preventing various metabolic disorders. Understanding its associations with other genes, its roles in aging, and its potential drug interactions can provide insights into therapeutic strategies for related diseases.