5-Fluorouracil (5-FU) Toxicity and Chemotherapeutic Response, 7 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.
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, 7 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 (DPYD) 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 and Specificity:
Unknown

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:




Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.

See Compliance Statement C: www.aruplab.com/CS
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.-​1590 T>C N/A 0.007 -​ French Caucasians Decreased DPYD activity;
Increased toxicity risk
c.85 T>C DPYD*9A 0.185 -​ French Caucasians Decreased DPYD activity;
Increased toxicity risk
c.1679 T>G DPYD*13 0.001 -​ French Caucasians Decreased DPYD activity;
Increased toxicity risk
c.1905+1 G>A IVS14+1 G>A; DPYD*2A Absent -​ Japanese, Korean, African American
0.0047 -​ 0.022-​Dutch, German, French, Turkish, Finnish
Abolished DPYD activity;
Greatly increased toxicity risk;
Increased risk of toxicity-​related death
c.2846 A>T N/A 0.01 -​ French Caucasians Decreased DPYD 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)
INSERTION 0.705 -​ Caucasian Increased TYMS expression;
Decreased 5-​FU responsiveness;
Decreased risk of toxicity
3'-​UTR:
6 bp deletion (TTAAAG)
DELETION 0.295 -​ Caucasian Decreased TYMS expression;
Increased 5-​FU responsiveness;
Increased risk of toxicity
5'-​TSER:
28bp VNTR (2R; 3R)

G>C SNP in 2nd repeat of 3R allele (3RC)
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)

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

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

G>C SNP in 2nd repeat of 3R allele (3RC)
3RC 0.15-​0.33 -​ Caucasian, Hispanic, African-​American
0.30 -​ Singapore, Chinese
0.399 -​ Japanese
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 Name
20024235-FU Tox,Response - DPYD c.85T>C
20024245-FU Tox,Response - DPYD c.1679T>G
20024255-FU Tox,Response - DPYD c.-1590T>C
20024265-FU Tox,Response - DPYD c.2846A>T
20072005-FU Tox,Response - Specimen
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, contact interface support at interface.support@aruplab.com.
Cross References
  • 5-FU Toxicity and Chemotherapeutic Response, 7 Mutations
  • DPYD and TYMS Genotyping, 7 Mutations
  • TYMS and DPYD Genotyping, 7 Mutations