NCPI FHIR Implementation Guide v2 - Local Development build (v0.2.0) built by the FHIR (HL7® FHIR® Standard) Build Tools. See the Directory of published versions

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ValueSet: Biological Relationship Codes

Official URL: https://nih-ncpi.github.io/ncpi-fhir-ig-2/ValueSet/family-biological-relationship-vs				Version: 0.2.0
Draft as of 2026-03-09				Computable Name: FamilyBiologicalRelationshipVS

All codes from the GA4GH KIN ontology for family relationships. This ValueSet duplicates the GA4GH PedigreeRelationshipTypes ValueSet to maintain compatibility with the GA4GH PedigreeRelationship profile while documenting NCPI-specific guidance.

NCPI-Recommended Codes for Maximum Interoperability

For maximum interoperability with other NCPI systems, prefer these three codes for genetic relationships in pedigrees (PED files):

• KIN:027 ("isBiologicalMotherOf"): The relative is the biological mother of the patient.
• KIN:028 ("isBiologicalFatherOf"): The relative is the biological father of the patient.
• KIN:010 ("isMonozygoticMultipleBirthSiblingOf"): The relative and patient are monozygotic twins. For higher-order multiples (triplets, quadruplets, etc.), create KIN:010 relationships between every pair of individuals in the multiple. Since this is a non-directed relationship, each pair requires two FamilyRelationship resources (A→B and B→A).

Relationships are expressed from relative (parent) to patient (child): relative=parent, patient=child, , relationship="isBiologicalMotherOf" or "isBiologicalFatherOf".

For other genetic relationships (grandparents, aunts, uncles, cousins), use these three codes with inferred individuals to represent the relationship chain.

Additional KIN Codes

The full KIN ontology provides 55 relationship codes including adoptive parents, step-relations, grandparents, and more. While all codes are available for use, NCPI systems may not fully support relationships beyond the three core codes listed above.

Future Enhancement

When FHIR R5/R6 support is added, we plan to use additional binding features to better express the preference for the three core codes while maintaining the full KIN ontology as an option.

References

• Family Relationship

Logical Definition (CLD)

 

Expansion

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Explanation of the columns that may appear on this page:

Level	A few code lists that FHIR defines are hierarchical - each code is assigned a level. In this scheme, some codes are under other codes, and imply that the code they are under also applies
System	The source of the definition of the code (when the value set draws in codes defined elsewhere)
Code	The code (used as the code in the resource instance)
Display	The display (used in the display element of a Coding). If there is no display, implementers should not simply display the code, but map the concept into their application
Definition	An explanation of the meaning of the concept
Comments	Additional notes about how to use the code