### PCDHB4 Gene Overview

**Gene Symbol:** PCDHB4  
**Gene Location:** Chromosome 5  
**Gene Cluster:** Protocadherin beta gene cluster

#### General Description
PCDHB4 is part of the protocadherin beta gene cluster, which plays a role in tissue and cell differentiation, particularly in the nervous system. It encodes a protein that includes six extracellular cadherin-like domains, facilitating cell-cell adhesion, which is believed to be critical for the formation and maintenance of neuronal circuits. 

### 1. Associated Genes
PCDHB4 is part of a larger family of protocadherins, specifically the protocadherin beta (PCDHB) cluster. Other members of the PCDHB cluster include:
- PCDHB1
- PCDHB2
- PCDHB3
- PCDHB5
- PCDHB6
- PCDHB7
- PCDHB9
- PCDHB10
- PCDHB11
- PCDHB12
- PCDHB13
- PCDHB14
- PCDHB15
- PCDHB16

It is worth noting that the protocadherin α (PCDHA) and γ (PCDHG) gene clusters are also relevant, as they have similar evolutionary origins and are likely to serve comparable functions in neuronal connectivity.

### 2. Aging and Age-related Diseases
Research on PCDHB4's direct association with aging or age-related diseases is limited. However, given its role in neuronal connections, dysregulation of PCDHB genes (including PCDHB4) has been implicated in neurodevelopmental and neurodegenerative disorders such as schizophrenia, Alzheimer's disease, and autism spectrum disorders. Additionally, alterations in cell adhesion molecules have been linked to cognitive decline and neuronal loss associated with aging.

### 3. Drug Interactions
As of my last update, there are no specific drugs directly interacting with PCDHB4. However, being involved in cell adhesion and signaling pathways, it may be indirectly affected by therapeutics used in neurology or psychiatry. Drugs that modify neural function or plasticity, such as certain antipsychotics, may correlate with the pathways involving PCDHB4, but specifics remain to be established.

### 4. Pathways and Biological Processes
PCDHB4 is thought to participate in several key biological pathways:
- **Cell adhesion:** Contributing to the establishment and maintenance of neural cell connections.
- **Neurodevelopment:** Involved in the development of neuron-specific connectivity and potentially influencing synaptic plasticity.
- **Signal transduction pathways:** Interaction with factors that regulate cellular activities in response to the neuronal environment.
- **Nervous system development:** Overall, essential for the proper development of various neuronal structures and functions.

In conclusion, PCDHB4 has a crucial function in cell adhesion related to neuronal connections but requires further investigation to fully elucidate its roles in aging, disease, and interaction with therapeutics.