The **FAM50B** gene (Family with Sequence Similarity 50 Member B) is an interesting gene with several attributes worth noting:

### 1. Associated Genes
While specific genes directly associated with **FAM50B** are not always fully disclosed or characterized, genes that often show epigenetic relationships or are located in similar genomic neighborhoods can include:

- **FAM50A**: A paralog of FAM50B, it is known to share similarities in evolutionary history and potential functional relationships.
- **IGF2**: Since FAM50B lies near differentially methylated regions, genes like IGF2, which are subject to genomic imprinting, may be functionally related due to their roles in growth and development.

### 2. Aging and Age-Related Diseases
Current research is limited, but some implications can potentially be drawn from its expression patterns and relationships:

- **Circadian Rhythm**: The connection to a plant protein involved in the circadian clock suggests that disruptions in circadian rhythms, which are often observed in aging, might implicate FAM50B in age-related metabolic or neurodegenerative disorders.
- **Neurodevelopment**: The gene's expression in the fetal and adult brain indicates a potential role in neurodevelopmental processes, which may be relevant in age-related cognitive decline or disorders such as Alzheimer’s disease.

### 3. Drug Interactions
There is currently insufficient specific information regarding drugs or drug classes directly interacting with **FAM50B**. However, given its expression in the testis and brain, drugs that target neurological or reproductive processes might indirectly interact with the gene's expression. 

### 4. Pathways and Biological Processes
FAM50B has been implicated in various biological processes, but specific pathways are still being elucidated. Some inferred roles include:

- **Gene Regulation**: Being a paternally expressed imprinted gene, FAM50B plays a role in genomic imprinting and transcriptional regulation processes.
- **Circadian Rhythm**: Given its relation to circadian clock-associated proteins in plants, it might be involved in the regulation of biological rhythms and processes related to cellular cycles.

To conclude, FAM50B is an intriguing gene with particular roles in gene expression regulation and possibly in the circadian rhythm, albeit further studies are necessary to elucidate its comprehensive functions and pathological implications, especially related to aging and age-associated diseases. Further research is required to better understand its interactions with drugs and confirm pathways involved definitively.