curl -G "https://api.omophub.com/v1/concepts/201826/relationships/Is%20a" \
-H "Authorization: Bearer YOUR_API_KEY" \
--data-urlencode "page_size=20"
{
"success": true,
"data": [
{
"concept_id_1": 201826,
"concept_id_2": 201820,
"relationship_id": "Is a",
"relationship_name": "Is a",
"reverse_relationship_id": "Subsumes",
"concept_1": {
"concept_id": 201826,
"concept_name": "Type 2 diabetes mellitus",
"concept_code": "44054006",
"vocabulary_id": "SNOMED",
"vocabulary_name": "Systematic Nomenclature of Medicine - Clinical Terms (IHTSDO)",
"domain_id": "Condition",
"concept_class_id": "Disorder",
"standard_concept": "S",
"valid_start_date": "2002-01-31T00:00:00.000Z",
"valid_end_date": "2099-12-31T00:00:00.000Z",
"invalid_reason": null
},
"concept_2": {
"concept_id": 201820,
"concept_name": "Diabetes mellitus",
"concept_code": "73211009",
"vocabulary_id": "SNOMED",
"vocabulary_name": "Systematic Nomenclature of Medicine - Clinical Terms (IHTSDO)",
"domain_id": "Condition",
"concept_class_id": "Disorder",
"standard_concept": "S",
"valid_start_date": "2002-01-31T00:00:00.000Z",
"valid_end_date": "2099-12-31T00:00:00.000Z",
"invalid_reason": null
},
"valid_start_date": "2011-07-31T00:00:00.000Z",
"valid_end_date": "2099-12-31T00:00:00.000Z",
"invalid_reason": null
}
],
"meta": {
"request_id": "7833dc90-cbc3-4034-9ebe-9219330d8f9e",
"timestamp": "2026-09-12T22:28:47.416Z",
"vocab_release": "2026.2",
"pagination": {
"page": 1,
"page_size": 20,
"total_items": 1,
"total_pages": 1,
"has_next": false,
"has_previous": false
}
}
}
Get Concept Relationships by Type
Retrieve one relationship type for a concept using the relationship type as a path parameter.
curl -G "https://api.omophub.com/v1/concepts/201826/relationships/Is%20a" \
-H "Authorization: Bearer YOUR_API_KEY" \
--data-urlencode "page_size=20"
{
"success": true,
"data": [
{
"concept_id_1": 201826,
"concept_id_2": 201820,
"relationship_id": "Is a",
"relationship_name": "Is a",
"reverse_relationship_id": "Subsumes",
"concept_1": {
"concept_id": 201826,
"concept_name": "Type 2 diabetes mellitus",
"concept_code": "44054006",
"vocabulary_id": "SNOMED",
"vocabulary_name": "Systematic Nomenclature of Medicine - Clinical Terms (IHTSDO)",
"domain_id": "Condition",
"concept_class_id": "Disorder",
"standard_concept": "S",
"valid_start_date": "2002-01-31T00:00:00.000Z",
"valid_end_date": "2099-12-31T00:00:00.000Z",
"invalid_reason": null
},
"concept_2": {
"concept_id": 201820,
"concept_name": "Diabetes mellitus",
"concept_code": "73211009",
"vocabulary_id": "SNOMED",
"vocabulary_name": "Systematic Nomenclature of Medicine - Clinical Terms (IHTSDO)",
"domain_id": "Condition",
"concept_class_id": "Disorder",
"standard_concept": "S",
"valid_start_date": "2002-01-31T00:00:00.000Z",
"valid_end_date": "2099-12-31T00:00:00.000Z",
"invalid_reason": null
},
"valid_start_date": "2011-07-31T00:00:00.000Z",
"valid_end_date": "2099-12-31T00:00:00.000Z",
"invalid_reason": null
}
],
"meta": {
"request_id": "7833dc90-cbc3-4034-9ebe-9219330d8f9e",
"timestamp": "2026-09-12T22:28:47.416Z",
"vocab_release": "2026.2",
"pagination": {
"page": 1,
"page_size": 20,
"total_items": 1,
"total_pages": 1,
"has_next": false,
"has_previous": false
}
}
}
Returns relationships whose
relationship_id exactly matches the path value.
For new integrations, prefer List Relationships for a Concept
with the relationship_ids query parameter; that endpoint also supports
validity, vocabulary, domain, direction, and standard-concept filters.
The path value is case-sensitive and may contain spaces. URL-encode values
such as
Is a as Is%20a.This compatibility shortcut includes invalid relationships and concepts. Use
the canonical relationship endpoint with
relationship_ids and the default
include_invalid=false when you only want current records.Path Parameters
integer
required
Concept whose outgoing relationships are returned.
string
required
Exact OMOP relationship identifier, for example
Is a or Maps to.Query Parameters
integer
default:"1"
Page number, using one-based indexing.
integer
default:"20"
Relationships per page. Values above 200 are clamped to 200.
string
Vocabulary release to query. When omitted, the current default release is
used.
Response
boolean
Whether the lookup completed.
array
Matching relationships for the requested page.
Show Relationship object
Show Relationship object
integer
Stored source concept identifier.
integer
Stored target concept identifier.
string
Relationship identifier matched by the path value.
string
Relationship display name.
string
Identifier for the reverse relationship.
object
Stored source concept.
Show Source concept
Show Source concept
integer
Concept identifier.
string
Concept name.
string
Source vocabulary code.
string
Vocabulary identifier.
string
Vocabulary name.
string
OMOP domain.
string
Concept class.
string|null
Standard-concept flag.
string
Validity start timestamp.
string
Validity end timestamp.
string|null
Invalidity marker, or
null.object
Stored target concept.
Show Target concept
Show Target concept
integer
Concept identifier.
string
Concept name.
string
Source vocabulary code.
string
Vocabulary identifier.
string
Vocabulary name.
string
OMOP domain.
string
Concept class.
string|null
Standard-concept flag.
string
Validity start timestamp.
string
Validity end timestamp.
string|null
Invalidity marker, or
null.string
Relationship validity start timestamp.
string
Relationship validity end timestamp.
string|null
Relationship invalidity marker, or
null.object
Show Response metadata
Show Response metadata
string
Unique request identifier.
string
ISO 8601 response timestamp.
string
Vocabulary release used.
curl -G "https://api.omophub.com/v1/concepts/201826/relationships/Is%20a" \
-H "Authorization: Bearer YOUR_API_KEY" \
--data-urlencode "page_size=20"
{
"success": true,
"data": [
{
"concept_id_1": 201826,
"concept_id_2": 201820,
"relationship_id": "Is a",
"relationship_name": "Is a",
"reverse_relationship_id": "Subsumes",
"concept_1": {
"concept_id": 201826,
"concept_name": "Type 2 diabetes mellitus",
"concept_code": "44054006",
"vocabulary_id": "SNOMED",
"vocabulary_name": "Systematic Nomenclature of Medicine - Clinical Terms (IHTSDO)",
"domain_id": "Condition",
"concept_class_id": "Disorder",
"standard_concept": "S",
"valid_start_date": "2002-01-31T00:00:00.000Z",
"valid_end_date": "2099-12-31T00:00:00.000Z",
"invalid_reason": null
},
"concept_2": {
"concept_id": 201820,
"concept_name": "Diabetes mellitus",
"concept_code": "73211009",
"vocabulary_id": "SNOMED",
"vocabulary_name": "Systematic Nomenclature of Medicine - Clinical Terms (IHTSDO)",
"domain_id": "Condition",
"concept_class_id": "Disorder",
"standard_concept": "S",
"valid_start_date": "2002-01-31T00:00:00.000Z",
"valid_end_date": "2099-12-31T00:00:00.000Z",
"invalid_reason": null
},
"valid_start_date": "2011-07-31T00:00:00.000Z",
"valid_end_date": "2099-12-31T00:00:00.000Z",
"invalid_reason": null
}
],
"meta": {
"request_id": "7833dc90-cbc3-4034-9ebe-9219330d8f9e",
"timestamp": "2026-09-12T22:28:47.416Z",
"vocab_release": "2026.2",
"pagination": {
"page": 1,
"page_size": 20,
"total_items": 1,
"total_pages": 1,
"has_next": false,
"has_previous": false
}
}
}
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