This code system http://hl7.org/fhir/genomicstudy-changetype defines the following codes:

CodeDisplayDefinition
DNA DNA changeChange that involves Deoxyribonucleic acid (DNA) sequences.
RNA RNA changeChange that involves Ribonucleic Acid (RNA) sequences.
AA Protein/amino Acids change Change that involves Amino Acid (AA) or protein sequences.
CHR Chromosomal changesChange that involves number or strcture of chromosomes.
CNV Copy number variationsChange that involves copy number variations among various genomes.
<status value="active"/><experimental value="true"/><date value="2022-08-17T15:48:24-05:00"/><publisher value="HL7 (FHIR Project)"/><contact><telecom><system value="url"/><value value="http://hl7.org/fhir"/></telecom><telecom><system value="email"/><value value="fhir@lists.hl7.org"/></telecom></contact><description value="The change type relevant to GenomicStudy analysis."/><jurisdiction><coding><system value="http://unstats.un.org/unsd/methods/m49/m49.htm"/><code value="001"/><display value="World"/></coding></jurisdiction><caseSensitive value="true"/><valueSet value="http://hl7.org/fhir/ValueSet/genomicstudy-changetype"/><content value="complete"/><concept><code value="DNA"/><display value="DNA change"/><definition value="Change that involves Deoxyribonucleic acid (DNA) sequences."/></concept><concept><code value="RNA"/><display value="RNA change"/><definition value="Change that involves Ribonucleic Acid (RNA) sequences."/></concept><concept><code value="AA"/><display value="Protein/amino Acids change "/><definition value="Change that involves Amino Acid (AA) or protein sequences."/></concept><concept><code value="CHR"/><display value="Chromosomal changes"/><definition value="Change that involves number or strcture of chromosomes."/></concept><concept><code value="CNV"/><display value="Copy number variations"/><definition value="Change that involves copy number variations among various genomes."/></concept></CodeSystem>