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curl "https://api.omophub.com/v1/relationships/types?page_size=50" \
  -H "Authorization: Bearer YOUR_API_KEY"

{
  "success": true,
  "data": {
    "relationship_types": [
      {
        "relationship_id": "Is a",
        "relationship_name": "Is a",
        "is_hierarchical": "1",
        "defines_ancestry": "1",
        "reverse_relationship_id": "Subsumes",
        "relationship_concept_id": 44818821
      },
      {
        "relationship_id": "Maps to",
        "relationship_name": "Maps to",
        "is_hierarchical": "0",
        "defines_ancestry": "0",
        "reverse_relationship_id": "Mapped from",
        "relationship_concept_id": 44818981
      },
      {
        "relationship_id": "Has finding site",
        "relationship_name": "Has finding site",
        "is_hierarchical": "0",
        "defines_ancestry": "0",
        "reverse_relationship_id": "Finding site of",
        "relationship_concept_id": 44818788
      }
    ]
  },
  "meta": {
    "request_id": "req_abc123",
    "vocab_release": "2025.1",
    "pagination": {
      "page": 1,
      "page_size": 100,
      "total_items": 642,
      "total_pages": 7,
      "has_next": true,
      "has_previous": false
    }
  }
}
This endpoint returns all relationship types from the OMOP CDM RELATIONSHIP table, which defines the types of connections that can exist between concepts.

​
Query Parameters

​
page
integer
default:"1"
Page number for pagination (1-based)
​
page_size
integer
default:"100"
Number of relationship types to return per page (max 500)
​
vocab_release
string
Specific vocabulary release version
Example: 2025.1

​
Response

​
relationship_types
array
Array of relationship type objects from the OMOP CDM RELATIONSHIP table
​
meta
object
Response metadata including pagination
curl "https://api.omophub.com/v1/relationships/types?page_size=50" \
  -H "Authorization: Bearer YOUR_API_KEY"

{
  "success": true,
  "data": {
    "relationship_types": [
      {
        "relationship_id": "Is a",
        "relationship_name": "Is a",
        "is_hierarchical": "1",
        "defines_ancestry": "1",
        "reverse_relationship_id": "Subsumes",
        "relationship_concept_id": 44818821
      },
      {
        "relationship_id": "Maps to",
        "relationship_name": "Maps to",
        "is_hierarchical": "0",
        "defines_ancestry": "0",
        "reverse_relationship_id": "Mapped from",
        "relationship_concept_id": 44818981
      },
      {
        "relationship_id": "Has finding site",
        "relationship_name": "Has finding site",
        "is_hierarchical": "0",
        "defines_ancestry": "0",
        "reverse_relationship_id": "Finding site of",
        "relationship_concept_id": 44818788
      }
    ]
  },
  "meta": {
    "request_id": "req_abc123",
    "vocab_release": "2025.1",
    "pagination": {
      "page": 1,
      "page_size": 100,
      "total_items": 642,
      "total_pages": 7,
      "has_next": true,
      "has_previous": false
    }
  }
}

​
Usage Examples

​
All Relationship Types

Get all available relationship types: 
curl "https://api.omophub.com/v1/relationships/types" \
  -H "Authorization: Bearer YOUR_API_KEY"

​
Paginated Results

Navigate through pages of relationship types: 
curl "https://api.omophub.com/v1/relationships/types?page=2&page_size=50" \
  -H "Authorization: Bearer YOUR_API_KEY"

​
Notes

  • Relationship types come from the OMOP CDM RELATIONSHIP table
  • All relationships exist symmetrically (both directions)
  • Hierarchical relationships (like “Is a”) are used to build the CONCEPT_ANCESTOR table
  • The defines_ancestry field indicates which relationships contribute to ancestor computation
  • Each relationship type has a corresponding concept in the CONCEPT table