Companies Offering CYP2D6 Polymorphism Testing
The American College of Medical Genetics and Genomics (ACMG) recommends targeted next-generation sequencing (NGS) combined with specific copy number variant (CNV) detection assays for comprehensive CYP2D6 polymorphism testing, but does not specify particular commercial providers of such testing. 1
Testing Methodologies for CYP2D6 Polymorphisms
CYP2D6 testing requires specialized methodologies due to the complex nature of this gene locus, which includes:
- Detection of single nucleotide variants (SNVs) that define star (*) alleles
- Identification of copy number variants (CNVs) including deletions, duplications, and multiplications
- Analysis of gene rearrangements and CYP2D6/CYP2D7 hybrid genes
The ACMG technical standards highlight that comprehensive CYP2D6 testing should include:
- Targeted genotyping for common variants
- Copy number analysis to detect structural variations
- Phasing information when possible to determine if variants are on the same chromosome (in cis) or opposite chromosomes (in trans) 2
Testing Approaches and Their Limitations
Different testing approaches offer varying levels of comprehensiveness:
- Targeted genotyping assays: Rapid and lower cost, but only detect selected variants
- Exome sequencing: Detects variants in coding regions but may miss structural variations
- Genome sequencing: Most comprehensive but higher cost and longer analysis time 1
Clinical Significance of CYP2D6 Testing
CYP2D6 polymorphisms significantly impact drug metabolism for approximately 25% of clinically used medications 3, including:
- Antidepressants and antipsychotics
- Antiarrhythmics
- Beta-blockers (particularly metoprolol)
- Opioid analgesics (codeine, tramadol)
- Tamoxifen
The enzyme activity ranges from poor metabolizers (PMs) to ultrarapid metabolizers (UMs), affecting drug efficacy and safety 3.
Common Pitfalls in CYP2D6 Testing
- Incomplete variant coverage leading to missed rare functional variants
- Overlooking CNVs resulting in incorrect phenotype assignment
- Misinterpreting heterozygous variants without phasing information
- Using only rs identifiers which can be ambiguous 1
Validation Requirements
ACMG recommends that laboratories establish performance characteristics during validation by:
- Running a minimum of 20 previously characterized samples
- Including samples that represent alleles/haplotypes detectable by the platform
- Testing both SNVs and CNVs
- Documenting concordance of expected results 2
While the question specifically asks which companies offer CYP2D6 polymorphism testing, the provided evidence does not list specific commercial providers. Clinical laboratories and reference laboratories offering pharmacogenomic testing would typically include CYP2D6 in their test panels, but specific company names are not mentioned in the evidence.