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PCR with capillary electrophoresis assays to detect mutations in the coding sequence of the UGT1A1 gene due to variations in the number of TA repeats in the TATA box of the UGT1A1 gene promoter. This test can report the following alleles: (TA)5 (UGT1A1*36),(TA)6 (UGT1A1*1), (TA)7 (UGT1A1*28), and (TA)8 (UGT1A1*37).
The UGT1A1 activity is responsible for the metabolic inactivation of SN-38 (active form of Irinotecan, also known as Camptosar® or CPT-11), therefore these mutations increase the risk of toxicity following its administration, due to the presence of elevated levels of unconjugated SN-38.
Several clinical studies have shown that individuals who are homozygous, and potentially those who are heterozygous, for the UGT1A1 (TA)7 promoter allele (UGT1A1*28) are at increased risk for the development of a significant adverse response to the standard dose of Irinotecan.
The result provides valuable information to initiate or modify treatment in a broad spectrum of solid tumors, e.g. metastatic cancer of the colon or rectum. The variants have also been reported in patients with disorders of bilirubin metabolism, such as Crigler-Najjar Types I and II, as well as Gilbert syndrome.
Synonyms: Gilbert Syndrome,Uridine Diphosphate Glucuronyltransferase 1A1 Promoter Genotyping, Irinotecan Sensitivity Analysis
Whole blood (5 mL), Bone marrow(2 mL), in Lavender-top (EDTA) tube. ACD (yellow top) and heparin (green top)are acceptable and DNA also, if extracted in a CLIA certified laboratory.
Within 48 hours of collection, use cold pack for transport. Make sure cold pack is not in direct contact with specimen. Do not freeze the sample.