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Molecular genetic testing is a critical procedure that focuses on identifying specific mutations within the CYP2C9 gene, which is located on chromosome 10. This gene encodes for the cytochrome P450, family 2, subfamily C, polypeptide 9, a complex protein that plays a vital role in the metabolism of various xenobiotics—substances that are foreign to the body, including drugs and toxins. The cytochrome P450 enzymes are essential for the bioactivation and synthesis of numerous biological compounds, such as cholesterol, steroids, and other lipids. Within the CYP2C9 gene, at least 50 single nucleotide polymorphisms (SNPs) have been identified in coding regions, which are linked to decreased enzyme activity. These genetic variations can lead to adverse drug reactions, often due to unexpected alterations in enzymatic function caused by polymorphisms. Notably, the common variants *2 and *3 are associated with a reduced capacity to metabolize warfarin, a commonly prescribed anticoagulant. Patients with these mutations typically require lower doses of warfarin to achieve therapeutic effects and are at a heightened risk for bleeding complications. Additionally, low-frequency variants such as *5 and *6 have been observed predominantly in African-American populations, with *5 associated with decreased enzyme activity and *6 linked to a complete lack of activity. Genetic testing for CYP2C9 mutations is particularly important for individuals undergoing specific drug therapies, such as those involving warfarin and phenytoin, as it helps identify genetic factors that may alter drug metabolism, potentially leading to toxicity even at standard therapeutic dosages.
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The CYP2C9 gene analysis is indicated for individuals who are undergoing certain types of drug therapy, particularly those involving anticoagulants like warfarin and anticonvulsants such as phenytoin. The testing is essential for patients who may be at risk of adverse drug reactions due to genetic variations that affect drug metabolism.
The procedure for CYP2C9 gene analysis involves several key steps to ensure accurate identification of genetic variants. Initially, a sample is collected from the patient, typically through a blood draw or saliva sample, which contains the DNA necessary for analysis.
After the CYP2C9 gene analysis, patients may not require any specific post-procedure care, as the testing is non-invasive and does not typically result in complications. However, it is essential for healthcare providers to discuss the results with the patient, explaining how the identified genetic variants may affect their medication regimen. Based on the findings, adjustments to drug dosages may be necessary to optimize therapeutic outcomes and minimize the risk of adverse effects. Patients should be monitored for any signs of drug toxicity or inadequate therapeutic response, particularly if they are on medications like warfarin or phenytoin, as these can have significant implications for their health and safety.
| Short Descr | CYP2C9 GENE COM VARIANTS | Medium Descr | CYP2C9 GENE ANALYSIS COMMON VARIANTS | Long Descr | CYP2C9 (cytochrome P450, family 2, subfamily C, polypeptide 9) (eg, drug metabolism), gene analysis, common variants (eg, *2, *3, *5, *6) | Status Code | Statutory Exclusion (from MPFS, may be paid under other methodologies) | Global Days | XXX - Global Concept Does Not Apply | PC/TC Indicator (26, TC) | 9 - Not Applicable | Multiple Procedures (51) | 9 - Concept does not apply. | Bilateral Surgery (50) | 9 - Concept does not apply. | Physician Supervisions | 09 - Concept does not apply. | Assistant Surgeon (80, 82) | 9 - Concept does not apply. | Co-Surgeons (62) | 9 - Concept does not apply. | Team Surgery (66) | 9 - Concept does not apply. | Diagnostic Imaging Family | 99 - Concept Does Not Apply | CLIA Waived (QW) | No | APC Status Indicator | Service Paid under Fee Schedule or Payment System other than OPPS | Type of Service (TOS) | 5 - Diagnostic Laboratory | Berenson-Eggers TOS (BETOS) | T1H - Lab tests - other (non-Medicare fee schedule) | MUE | 1 | CCS Clinical Classification | 234 - Pathology |
| 59 | Distinct procedural service: under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-e/m services performed on the same day. modifier 59 is used to identify procedures/services, other than e/m services, that are not normally reported together, but are appropriate under the circumstances. documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. however, when another already established modifier is appropriate it should be used rather than modifier 59. only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. note: modifier 59 should not be appended to an e/m service. to report a separate and distinct e/m service with a non-e/m service performed on the same date, see modifier 25. | 90 | Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number. | XU | Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service | GW | Service not related to the hospice patient's terminal condition | 91 | Repeat clinical diagnostic laboratory test: in the course of treatment of the patient, it may be necessary to repeat the same laboratory test on the same day to obtain subsequent (multiple) test results. under these circumstances, the laboratory test performed can be identified by its usual procedure number and the addition of modifier 91. note: this modifier may not be used when tests are rerun to confirm initial results; due to testing problems with specimens or equipment; or for any other reason when a normal, one-time, reportable result is all that is required. this modifier may not be used when other code(s) describe a series of test results (eg, glucose tolerance tests, evocative/suppression testing). this modifier may only be used for laboratory test(s) performed more than once on the same day on the same patient. | GA | Waiver of liability statement issued as required by payer policy, individual case | GY | Item or service statutorily excluded, does not meet the definition of any medicare benefit or, for non-medicare insurers, is not a contract benefit | GZ | Item or service expected to be denied as not reasonable and necessary | XS | Separate structure, a service that is distinct because it was performed on a separate organ/structure |
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| 2012-01-01 | Added | Added |
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