### SEMA3D Gene Overview

**Gene Symbol:** SEMA3D  
**Function:** The SEMA3D gene encodes a member of the semaphorin family, specifically the semaphorin III subfamily, which plays critical roles in neuronal development and cardiovascular development. The encoded protein is involved in axon guidance and influences neuronal growth cones by inducing collapse and paralysis.

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### 1. Associated Genes
SEMA3D may have connections to several other genes and pathways, which are crucial for its signaling and functional processes, including:

- **PLXNA1, PLXNB1, and PLXNB2:** Plexins that act as receptors to semaphorins.
- **NRP1 and NRP2:** Neuropilins that interact with semaphorins, mediating their function.
- **RHOA and RAC1:** Small GTPases involved in cytoskeletal dynamics influenced by semaphorin signaling.
- **VEGFA:** Vascular endothelial growth factor A, involved in angiogenesis, which may intersect with semaphorin signaling pathways. 

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### 2. Aging and Age-Related Diseases
While direct associations of SEMA3D with aging or age-related diseases are not extensively documented, research on the semaphorin family suggests their involvement in:

- **Neurodegenerative diseases:** Given the role of SEMA3D in neuronal development, alterations in signaling may contribute to conditions like Alzheimer's disease or other forms of dementia.
- **Cardiovascular aging:** Dysfunctional signaling pathways in the semaphorin family may impact heart development and could contribute to age-related cardiovascular diseases.
  
**Note:** More specific studies would be needed to directly link SEMA3D to these conditions.

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### 3. Drug Interactions
As of the current knowledge up to October 2023, direct drug interactions with SEMA3D are not well characterized publicly in major databases. However, general categories of drugs that may affect semaphorin signaling pathways include:

- **Antineoplastic agents:** These may indirectly affect pathways involving SEMA3D in terms of tumor growth inhibition or promotion through regulation of angiogenesis.
- **Neurological drugs:** Medications targeting neural pathways could potentially interact indirectly with signaling pathways involving SEMA3D.

Emerging research might present insights into such interactions, but they remain largely under-explored.

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### 4. Pathways and Biological Processes
SEMA3D is involved in various biological pathways and processes:

- **Axon Guidance:** Its primary role in nervous system development involves guiding axons to their appropriate targets.
- **Cardiovascular Development:** SEMA3D is crucial for proper vascular patterning and heart morphogenesis.
- **Cell Migration and Adhesion:** It may influence the migration of various cell types through interactions with its receptors.
- **Eph signaling pathway:** SEMA3D may intersect with Ephrin signaling, which is crucial for neuronal and vascular development.

**Additional Biological Processes:**
- **Wound healing:** Through roles in angiogenesis and cell migration.
- **Inflammation:** Modulation of immune responses, though specific details need more research.

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This detailed overview encapsulates the SEMA3D gene's structure, functions, and implications while addressing associated genes, aging relevance, potential drug interactions, and pathways it participates in.