Not Persuasive with Mod: Keep as CodeableConcept, add the following text to the IG near the discussion of Genotype: Genotype is used to convey corresponding haplotypes or variations at a particular locus - for instance, [1] "TPMT *1/*3A" represents the TPMT *1 haplotype (or 'star allele') on one chromosome and the TPMT *3A haplotype on the homologous chromosome; [2] "A/C" represents a heterozygous "A" and a heterozygous "C" at SNP rs1142345 . Many genotypes are expressed as simple strings, and can be conveyed in genotype.valueCodeableConcept.text. In some cases, genotypes are sufficiently standardized to be conveyed as codes (in genotype.valueCodeableConcept.code). For HLA, KIR, and other genes in the immunogenetics domain, the National Marrow Donor Program (NMDP) led a community effort to define the Genotype List String (GL String) grammar, described here . Notably, the GL String uses '+' as a delimiter between alleles in a genotype. It also has delimiters for ambiguous genotypes, allele lists, and haplotypes. For Pharmacogenomics, we define here a simple grammar of [HGNC gene symbol followed by white space followed by a slash ('/') delimited list of haplotype codes] , where the codeSystem is set to the codeSystem of the haplotypes (e.g. Pharmvar). Here's some examples: Text only: <valueCodeableConcept> <text>A/C at SNP rs1142345</text> </valueCodeableConcept> Coded HLA <valueCodeableConcept> <coding> <system value=" http://glstring.org"/ > <version value="1.0"/> <code value=" [hla|3.23] HLA-A*01:01:01:01/HLA-A*01:02+HLA-A*24:02:01:01"/> </coding> </valueCodeableConcept> Coded PGx <valueCodeableConcept> <coding> <system value=" https://www.pharmvar.org/ "/> <code value=value="CYP2C9 *1A/*1A"/> </coding> </valueCodeableConcept>