Guided case: *1/*4 with a medication overlay

An adult starting tamoxifen has a validated targeted CYP2D6 panel with copy-number analysis detecting *1/*4. The allele function values are 1.0 and 0, so the activity score is 1.0 + 0 = 1.0.

Using the current standardized CYP2D6 thresholds, activity score 1.0 maps to Intermediate Metabolizer. The report records a patient identifier and accession to prevent identity swaps; method and tested allele/copy-number scope so *1 or a negative result is not read as excluding untested rare, hybrid, converted, or phased variants; and the diplotype so a haplotype pair is not reduced to one variant. It records the activity score and predicted phenotype so translation is not mistaken for measured enzyme activity, limitations or a no-call so uncertainty is not read as normal, and the evidence version/date for traceability. Its stated population-level coverage is not an individual guarantee.

The medication list includes paroxetine, an FDA-classified strong CYP2D6 inhibitor. A described clinical heuristic gives 1.0 times 0, or adjusted activity score 0, while the inhibitor is present. This is an approximation of functional capacity, not a new genotype or a direct measurement. Preserve the genotype-based Intermediate Metabolizer report and communicate the interacting-drug context as a separate clinical factor.