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UDP Glucuronosyltransferase 1A1

Item Value
Approval req'd? No
Available Stat? No
Test code UGT1A1
Performed by Medical Genomics - Molecular Diagnostics
In House Availability Batched assay performed once every 2 weeks
Method PCR and Fragment analysis
Collection Instructions Avoid hemolysis. Due to stability issues these samples should only be collected at UCSF Monday through noon Friday.

Do not collect sample in heparin. Keep sample refrigerated for overnight or longer storage.

For UCSF Samples (from remote sites) Click here for sample collection instructions

For NON-UCSF Samples Click here for Requisition form & Account set-up instructions. Note we only do institutional billing.
Container type Lavender top
Amount to Collect 3 mL
Sample type EDTA whole blood
Preferred volume 3 mL
Min. Volume 1 mL
UCSF Rejection Criteria Insufficient sample received.
Processing notes Do not freeze blood. Refrigerate sample if storage is required.

Ship to China Basin Molecular Diagnostics
Ref Lab Rejection Criteria Insufficient sample received. Serum, citrated or heparinized plasma received. Samples > 5 days old when received
Normal range
Wildtype *1/*1

(Most common normal allele is 6 repeats (= *1)
Synonyms Irenotecan; UGT1A1; UGT 1A1
Stability Refrigerated, 1 month.
Turn around times 10-14 days
Additional information An interpretation of this test by a laboratory physician will automatically be performed and billed for separately.

Irinotecan is used for the treatment of metastatic carcinoma of the colon or rectum. It causes severe neutropenia and diarrhea in 20-35% of patients undergoing chemotherapy. The ability to predict toxicity in treated patients is an important consideration.

UGT1A1 catalyzes the inactivation of SN-38, the active and toxic metabolite of irinotecan. The 7TA repeat length polymorphism (termed *28 allele) in the UGT1A1 promoter is associated with decreased UGT1A1 gene expression levels, resulting in lower than normal UGT1A1 enzymatic activity and accumulation of SN-38, the active irinotecan metabolite.

About 15% of North Americans are homozygous for the *28/*28 genotype and thus cancer patients carrying this variant exhibit irinotecan related toxicity and would require lower doses of irinotecan than patients carrying the 6 TA repeat (*1 allele). The clinical significance of the rare 5 and 8 TA repeats, termed *36 and *37 allele, respectively, in predicting irinotecan toxicities is not well established.
CPT coding 81350
LOINC code 51951-2
LDT or Mod FDA? Yes
Last Updated 6/25/2015 10:58:41 AM
Entry Number 1165
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