Required section · Section 3 of 6

Method scope sets the boundary

A targeted genotyping panel measures its specified variants. Sequencing may interrogate a broader sequence space, but it still needs validated copy-number and phasing rules. Neither method makes an untested variant disappear from the differential.

CYP2D6 sits beside pseudogenes CYP2D7 and CYP2D8. A *5 deletion, duplications, and CYP2D7-derived hybrid or converted alleles such as *36 can confound a simple small-nucleotide-variant panel or copy-number result. The report must name the tested allele and copy-number scope so *1, a negative result, or a no-call is not read as excluding untested rare, hybrid, converted, or phased variants. Coverage is a population-level estimate, not an individual guarantee.

A no-call means the laboratory cannot reliably assign a result for a stated target. It is not negative, wild type, or normal metabolizer. When scope, phase, or copy number is unresolved, release the limitation or no-call according to local policy rather than forcing a phenotype.

Same CYP2D6 question across two method approaches
Method	Measured target	Output	Principal limitation
Targeted allele-specific PCR/probe panel with CNV	Specified Tier 1 alleles and validated deletion/duplication targets	Detected variants, diplotype when resolvable	Rare, novel, hybrid, or untested alleles are not excluded; population-level coverage is not an individual guarantee
Sequencing with validated CNV and phasing workflow	Broader sequence interrogation plus structural rules	Additional sequence variants and interpreted structure when resolvable	Complex hybrids, phase, and copy number still need validated resolution

Knowledge checks

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Knowledge check 1

Which limitations should be considered for a targeted CYP2D6 panel?

Choose at least 3 options.

Untested rare or novel alleles may remain unexcluded.

Hybrid or converted alleles can challenge simple interpretation.

Unresolved phase can limit diplotype assignment.

A no-call can be released as Normal Metabolizer.

Knowledge check 2

What is the appropriate meaning of a CYP2D6 no-call?

Choose one option.

The target cannot be reliably assigned under the stated method.

No variant was detected, so the result is wild type.

The patient is a normal metabolizer.

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