### Gene Summary: ART4

The ART4 gene, encoding a member of the ADP-ribosyltransferase family, is primarily implicated in the Dombrock blood group system through its protein product. This gene is located on the erythrocyte membrane, anchored by glycosylphosphatidylinositol, and is primarily expressed in immune-related tissues including the spleen and T-cells.

### 1. Associated Genes
While the summary provided does not mention specific association with other genes, ART4 may be correlated with genes involved in blood group systems and immune response such as:
- **ACAN**: Involved in glycosylation patterns relevant to the ribosylation function.
- **GPIHBP1**: Interacting with glycosylphosphatidylinositol-anchored proteins.
- **RAT**: Another gene encoding an ADP-ribosyltransferase which could show functional overlap.

### 2. Aging and Age-related Diseases
Currently, there is limited specific information directly linking ART4 to aging or age-related diseases. However, since ART4 is expressed in immune cells, one might imply potential associations with aging due to the immune system's function and changes that occur with advancing age, such as:
- **Immunosenescence**: The aging of the immune system may be partially influenced by protein interactions and modifications by ADP-ribosyltransferases like ART4, affecting immune responses and inflammation.
- **Autoimmune Diseases**: Variants leading to adverse reactions could have implications in age-related autoimmune diseases, although specific studies are necessary to clarify this.

### 3. Drug Interactions
As the enzyme activity of the ART4 protein has not been experimentally demonstrated, specific interactions with drugs are not well established. Nonetheless, potential interactions could be postulated based on the enzyme family to which it belongs:
- **Nicotinamide adenine dinucleotide (NAD+) analogs**: May affect ADP-ribosylation activities in related contexts.
- **Immunomodulatory drugs**: As ART4 is involved in T-cell functions, drugs targeting the immune system could indirectly impact its pathways.

### 4. Pathways and Biological Processes
ART4 is believed to be involved in several biological pathways and processes:
- **ADP-ribosylation**: Though unproven, ART4 is expected to be involved in post-translational modifications via mono-ADP-ribosylation.
- **Immunity**: As it is expressed in T-cells and spleen tissue, it likely plays a role in immune signaling pathways.
- **Erythrocyte Membrane Biology**: Given its anchorage in cell membranes, ART4 could influence membrane dynamics and cellular interactions in erythrocytes.
- **Blood Group Antigen Expression**: Plays a role in the genetic diversity of blood group antigens, which can have clinical significance in transfusions and organ transplants.

### Conclusion
While ART4 is one of the lesser-studied members of the ADP-ribosyltransferase family, its implications in blood group biology and immune response systems are notable. Research into its full functional capacity, particularly concerning its role in aging and disease, represents a valuable field of exploration in genetics and immunology.