This is the ValueSet that contains all the codes in HUGO Gene Nomenclature Committee Gene Names (HGNC) (http://hl7.org/fhir/uv/genomics-reporting/ValueSet/hgnc-vs) and HUGO Gene Nomenclature Committee Gene Names (HGNC) (http://hl7.org/fhir/uv/genomics-reporting/ValueSet/hgnc-vs). E.g. what you have to deal with if you get resources containing codes in either of them