This document addresses genotype testing for individual polymorphisms which can identify variants of specific genes associated with abnormal and normal drug metabolism. Such testing is used to identify individuals with certain gene variants which may potentially be able to receive higher or lower doses of some drugs, or should avoid some drugs altogether, to improve the likelihood of achieving clinical goals as well as lessening the risk of adverse drug effects.

Testing for NS3 Q80K for individuals being treated for Hepatitis C virus is NOT addressed in this document.

Note: For additional information regarding pharmacogenomics, please see:

• CG-GENE-10 Chromosomal Microarray Analysis (CMA) for Developmental Delay, Autism Spectrum Disorder, Intellectual Disability and Congenital Anomalies
• CG-GENE-13 Genetic Testing for Inherited Diseases
• GENE.00010 Panel and other Multi-Gene Testing for Polymorphisms to Determine Drug-Metabolizer Status

Clinical Indications

Medically Necessary:

Genotype testing for genetic polymorphisms of Human Leukocyte Antigen B*1502 (HLA-B*1502) to determine the drug-metabolizer status of individuals for whom the use of carbamazepine is being proposed is considered medically necessary when both of the criteria below have been met:

1. The individual is from a population who is at high risk due to ethnic heritage; and
2. There are no other alternatives to the use of carbamazepine.

Genotype testing for identification of the CYP2C19 variant of Cytochrome P450 is considered medically necessary to determine the drug-metabolizer status of individuals who meet either of the following criteria:

1. The individual is currently undergoing treatment with clopidogrel and has not been tested: or
2. The use of clopidogrel is being proposed.

Genotype testing for Human Leukocyte Antigen B (HLA-B*5701) is considered medically necessary before beginning treatment with abacavir for persons infected with HIV-1.

Genotype testing for identification of the CYP2D6 variant of Cytochrome P450 to determine the drug-metabolizer status of individuals being considered for treatment with eliglustat is considered medically necessary.

Genotype testing for identification of the CYP2D6 variant of Cytochrome P450 to determine the drug-metabolizer status of individuals with Huntington’s disease being considered for treatment with a dosage of tetrabenazine greater than 50 mg per day is considered medically necessary.

Genotype testing to determine the presence of the HLA-B*58:01 allele in individuals from a population who are at high risk due to ethnic heritage for whom the use of allopurinol is being considered for treatment is considered medically necessary.

Genotype testing to determine the presence of CYP2C9 genotype before administration of siponimod is considered medically necessary.

Genotype testing for individual genetic polymorphisms to determine thiopurine methyltransferase (TPMT) genotype is considered medically necessary prior to the initiation of thiopurine medication when the results of phenotype testing is indeterminate.

Not Medically Necessary:

Genotype testing for individual genetic polymorphisms for individuals who potentially may receive the drugs listed above is considered not medically necessary when the criteria or circumstances detailed above are not met.

Genotype testing for individual genetic polymorphisms to determine drug-metabolizer status is considered not medically necessary in all other circumstances.