### CLDN4 Gene Overview

**Gene Symbol:** CLDN4  
**Location:** Chromosome 7q11.23  
**Gene Type:** Protein-coding  

**Function:** The CLDN4 gene encodes a member of the claudin family of proteins, integral components of tight junctions in epithelial cells. These junctions are crucial for maintaining the integrity of epithelial barriers, regulating paracellular transport of ions and solutes, and ensuring proper cell adhesion. Specifically, CLDN4 functions as a high-affinity receptor for Clostridium perfringens enterotoxin (CPE) and is significant in the development and function of internal organs, as well as in the reabsorption of chloride in kidney collecting ducts.

### Additional Information

1. **Associated Genes:**
   - **CLDN1, CLDN2, CLDN3, CLDN5, CLDN7,** and other claudin family members: The claudin proteins often work together in forming tight junctions.
   - **DMD:** Claudin-4 has been referenced in studies involving dystrophin (DMD), particularly considering its role in muscle cell integrity and function.
   - **APC (Adenomatous polyposis coli):** Association has been noted in cancer research, as Claudin-4 can affect pathways influenced by APC.

2. **Aging and Age-Related Diseases:**
   - Research has indicated that alterations in tight junctions and claudin expression may correlate with age-related changes in tissue permeability and regenerative capacity. CLDN4 may be implicated in age-related diseases such as neurodegeneration, as it plays roles in maintaining the blood-brain barrier.
   - Studies have suggested that dysregulation of CLDN4 expression can contribute to cancer initiation and progression, particularly in gastrointestinal cancers, which may be exacerbated in older adults.

3. **Drug Interactions:**
   - As of the latest data, there isn't a direct link to specific drugs being developed for or targeting CLDN4 exclusively. However, drugs that affect tight junction integrity and function (like certain anti-inflammatory medications) might indirectly influence the behavior of CLDN4.  
   - Drug classes including monoclonal antibodies being tested for targeting tight junctions or involved in cancer pathways (due to its role in mediating pathophysiological states) may relate to CLDN4's function.

4. **Pathways and Biological Processes:**
   - **Tight junction organization:** Fundamental for cell barrier integrity in epithelial tissues.
   - **Paracellular transport:** Specifically chloride ion transport in kidney cells.
   - **Developmental processes:** May play a critical role in differentiation and function of epithelial tissues during pre- and postnatal development.
   - **Pathways involved in epithelial differentiation:** Associated with pathways affecting cellular adhesion and morphology, impacting conditions such as cancer and developmental disorders.

### Summary
The CLDN4 gene is crucial for maintaining epithelial barrier function and plays a significant role in ion transport and possibly in developmental processes. Its interface with diseases like Williams-Beuren syndrome and potential roles in aging and cancer make it a gene of scientific interest. Further research into its interactions and biological roles could offer insights into therapeutic applications and the biological mechanisms underlying various diseases.