Example of a clinical gender observation. For a discussion on representing a patient's gender the Patient Resource.

{
  "resourceType" : "Observation",
  "id" : "clinical-gender",
  "status" : "final",
  "category" : [{
    "coding" : [{
      "system" : "http://terminology.hl7.org/CodeSystem/observation-category",
      "code" : "social-history",
      "display" : "Social History"
    }]
  }],
  "code" : {
    "coding" : [{
      "system" : "http://loinc.org",
      "code" : "76691-5",
      "display" : "Gender identity"
    }],
    "text" : "Gender identity"
  },
  "subject" : {
    "reference" : "Patient/example"
  },
  "encounter" : {
    "reference" : "Encounter/example"
  },
  "effectiveDateTime" : "2018-02-01",
  "performer" : [{
    "reference" : "Practitioner/example"
  }],
  "valueCodeableConcept" : {
    "coding" : [{
      "system" : "http://snomed.info/sct",
      "code" : "191788006",
      "display" : "Feminism in boy (finding)"
    }],
    "text" : "Feminism in boy"
  }
}