Build the result in four layers

The first layer is the assay observation, such as a targeted CYP2D6 variant call. The second is allele assignment and phasing into a diplotype, for example *1/*4. The third is a predicted phenotype derived from the diplotype using a stated translation system.

For CYP2D6, allele function values are summed into a unitless activity score, with duplicated alleles multiplied by copy number. Under the current standardized CPIC thresholds, an activity score of 0 is poor metabolizer, more than 0 to less than 1.25 is intermediate metabolizer, 1.25 to 2.25 is normal metabolizer, and more than 2.25 is ultrarapid metabolizer. This phenotype is a genotype-derived grouping, not a direct enzyme-activity measurement.

The fourth layer is an external gene-drug interpretation with a named source and version. Keep that layer visibly separate from the laboratory result because guidance and labels change. State which layer each sentence belongs to before it reaches the report.