5-Fluorouracil (5-FU) Toxicity and Chemotherapeutic Response, 5 Mutations
2007228
Ordering Recommendation
Predicts toxicity and responsiveness to 5-FU therapy.
Mnemonic
5-FU PANEL
Methodology
Polymerase Chain Reaction/Single Nucleotide Extensions/Fragment Analysis
Performed
Varies
Reported
10-14 days  
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Specimen Required
Patient Preparation
  
Collect
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).  
Specimen Preparation
Transport 3 mL whole blood. (Min: 1 mL)  
Storage/Transport Temperature
Refrigerated.  
Unacceptable Conditions
  
Remarks
  
Stability
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable  
Reference Interval
   
Interpretive Data
Background information for 5-Fluorouracil (5-FU) Toxicity and Chemotherapeutic Response, 5 Mutations:
Characteristics:
5-FU is the most frequently used chemotherapeutic drug for the treatment of many types of cancer, particularly colorectal adenocarcinoma. Grade III-IV drug toxicity attributed to 5-FU occurs in approximately 16 percent of patients, and may include hematologic, gastrointestinal, and dermatologic complications. In some cases, this toxicity can cause death. When 5-FU is metabolized in the body, approximately 80 percent is catabolized by the dihydropyrimidine dehydrogenase (DPD) enzyme. The remaining drug is further metabolized into an active form that inhibits the synthesis of both DNA and RNA by either competitive inhibition of the thymidylate synthase (TYMS) enzyme or by direct incorporation of cytotoxic metabolites into nucleic acids. Mutations in the DPYD gene can lead to reduced 5-FU catabolism, resulting in the aforementioned toxicity complications. The TYMS enzyme is the primary target of 5-FU. Mutations in the 5'-promoter enhancer region (5'-TSER) and the 3'-untranslated region (3'-UTR) of the TYMS gene have been correlated to TYMS expression levels, responsiveness to 5-FU therapy, and clinical outcome.
Clinical Sensitivity:
Estimated at 31 percent for the DYPD variants analyzed.
Methodology:
DPYD genotypes are determined by multiplex PCR, single nucleotide extension (SNE), and fragment analysis. TYMS genotypes are determined by PCR, restriction digest, and fragment analysis.
Analytical Sensitivity and Specificity:
99 percent.
Limitations:
Only the targeted TYMS and DPYD mutations will be detected by this panel. Diagnostic errors can occur due to rare sequence variations. 5-FU drug metabolism, efficacy and risk for toxicity may be affected by genetic and non-genetic factors that are not evaluated by this test. Genotyping does not replace the need for therapeutic drug monitoring or clinical observation.
Variants Tested:






See Compliance Statement C: www.aruplab.com/CS
Statement C: The performance characteristics of this test were validated by ARUP Laboratories. The U.S. Food and Drug Administration (FDA) has not approved or cleared this test; however, FDA approval or clearance is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. ARUP is authorized under Clinical Laboratory Improvement Amendments (CLIA) and by all states to perform high-complexity testing.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
 
Table 1. DPYD mutations: nomenclature, allele frequency, and predicted consequences
DPYD mutations Alternative name Allele frequency in
indicated population
Predicted consequence
in patients receiving 5-​FU
c.1679 T>G DPYD*13, rs55886062 0.001 -​ French Caucasians Decreased DPD activity;
Increased toxicity risk
c.1905+1 G>A DPYD*2A, IVS14+1 G>A, rs3918290 0.0047 -​ 0.022-​Dutch, German, French, Turkish, Finnish
Absent -​ Japanese, Korean, African American
Abolished DPD activity;
Greatly increased toxicity risk
c.2846 A>T rs67376798 0.01 -​ French Caucasians Decreased DPD activity;
Increased toxicity risk

 
Table 2. TYMS mutations, allele frequency, and predicted consequences
TYMS mutations Allele Allele frequency in
indicated population
Predicted consequence in
patients receiving 5-​FU
3'-​UTR:
6 bp deletion (TTAAAG)
(rs16430)
DELETION 0.295 -​ Caucasian Decreased TYMS expression;
Increased 5-​FU responsiveness;
Increased risk of toxicity
3'-​UTR:
6 bp deletion (TTAAAG)
(rs16430)
INSERTION 0.705 -​ Caucasian Increased TYMS expression;
Decreased 5-​FU responsiveness;
Decreased risk of toxicity
5'-​TSER
28bp VNTR (2R; 3R)
(rs45445694)
2R 0.41-​0.48 -​ Caucasian, Hispanic, African-​American
0.19 -​ Singapore, Chinese
0.175 -​ Japanese
2R/3RG:
Increased TYMS expression;
Decreased 5-​FU responsiveness;
Poor prognosis

2R/2R or 2R/3RC:
Decreased TYMS expression;
Increased 5-​FU responsiveness;
Increased risk of toxicity
5'-​TSER
28bp VNTR (2R; 3R)
(rs45445694)
3RG 0.51 -​ Singapore, Chinese
0.427 -​ Japanese
0.26-​0.37 -​ Caucasian, Hispanic, African-​American
3RG/3RG, 3RG/3RC or 2R/3RG :
Increased TYMS expression;
Decreased 5-​FU responsiveness;
Poor prognosis
5'-​TSER
G>C SNP in 2nd repeat of 3R allele
(3RC)
(rs34743033)
3RC 0.399 -​ Japanese
0.30 -​ Singapore, Chinese
0.15-​0.33 -​ Caucasian, Hispanic, African-​American
3RG/3RC:
Increased TYMS expression;
Decreased 5-​FU responsiveness;
Poor prognosis

3RC/3RC or 2R/3RC:
Decreased TYMS expression;
Increased 5-​FU responsiveness;
Increased risk of toxicity
Note
 
CPT Code(s)
81400, 81401,81479
Components
Component Test Code*Component Chart NameLOINC
20024245-FU Tox,Response - DPYD c.1679T>G45284-7
20024265-FU Tox,Response - DPYD c.2846A>T45284-7
20072005-FU Tox,Response - Specimen31208-2
20072295-FU Tox,Response - DPYD c.1905+1G>A 
20072305-FU Tox,Response - DPYD Interpretation 
20072315-FU Tox,Response - TYMS 3'UTR Genotype 
20072325-FU Tox,Response - TYMS 5'TSER Genotype 
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • 5-FU Toxicity and Chemotherapeutic Response, 7 Mutations
  • 5FU drug toxicity
  • Dihydropyrimidine
  • DPD
  • DPYD and TYMS Genotyping, 7 Mutations
  • DYPD
  • DYPD genotyping
  • TYMS and DPYD Genotyping, 7 Mutations
  • TYMS genotyping