The PPP1R3A gene is indeed an important contributor to glycogen metabolism through its role as a regulatory subunit of protein phosphatase-1 (PP1). Here's a detailed elaboration based on your requests:

### 1. Associated Genes
PPP1R3A is associated with several other genes, particularly those involved in glycogen metabolism and signaling pathways. Some of these include:
- **GYS1**: Glycogen synthase, which is directly involved in glycogen synthesis.
- **GPHL**: Glycogen phosphorylase, which is responsible for the breakdown of glycogen.
- **AKT1**: Protein kinase B, which is involved in signaling pathways that regulate glucose metabolism and glycogen synthesis.
- **PKA**: Protein kinase A, which is involved in phosphorylation processes that affect glycogen metabolism.

### 2. Aging and Age-Related Diseases
While specific studies directly tying PPP1R3A to aging or age-related diseases are limited, the regulation of glycogen metabolism is important in the context of metabolic syndrome, diabetes, and age-related decline in muscle mass (sarcopenia). Alterations in glycogen metabolism can contribute to insulin resistance, which is more prevalent with aging and can lead to type 2 diabetes and cardiovascular diseases. Research suggests that proper function of glycogen metabolism, where PPP1R3A plays a crucial role, is vital for skeletal muscle health in aging.

### 3. Drug or Drug Classes Interaction
While specific drugs targeting PPP1R3A may not be widely recognized, several classes of drugs may indirectly influence its activity through their effect on cellular signaling pathways associated with glycogen metabolism:
- **Insulin**: Insulin resistance can impact the action of PPP1R3A by modifying the phosphorylation status of glycogen synthase.
- **Biguanides** (such as Metformin): These can affect cellular energy metabolism and potentially influence glycogen synthesis indirectly.
- **Glitazones**: These are involved in enhancing insulin sensitivity and can have an indirect effect on glycogen metabolism.

### 4. Pathways and Biological Processes
PPP1R3A is involved in various biological processes and signaling pathways, including but not limited to:
- **Glycogen metabolism**: Central to the synthesis and degradation of glycogen.
- **Regulation of Protein Phosphorylation**: Influencing protein function and activity through dephosphorylation.
- **Muscle contraction**: By affecting the phosphorylation state of contractile proteins and glycogen-related enzymes.
- **Cell cycle regulation**: PP1 is known to play roles in progression through different phases of the cell cycle.

### Summary
Overall, PPP1R3A serves as a key regulatory element in glycogen metabolism, linking it with various physiological processes and potential implications in health and disease, particularly as they relate to energy balance, metabolism, and aging. Further research is necessary to elaborate on its roles in specific age-related conditions and its pharmacological targets.