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UGT1A1

From SNPedia
is agene
is mentioned by
Full nameUDP glucuronosyltransferase 1 family, polypeptide A1
EntrezGene54658
PheGenI54658
VariationViewer54658
ClinVarUGT1A1
GeneCardsUGT1A1
dbSNP54658
DiseasesUGT1A1
SADR54658
HugeNav54658
wikipediaUGT1A1
googleUGT1A1
gopubmedUGT1A1
EVSUGT1A1
HEFalMpUGT1A1
MyGene2UGT1A1
23andMeUGT1A1
UniProtP22309
EnsemblENSG00000241635
OMIM191740
# SNPs49
 Max MagnitudeChromosome positionSummary
rs10426400233,772,898
rs1110335390233,767,160
rs1110335400233,768,333
rs1110335410233,760,331
rs1149820900233,772,309
rs115632510233,770,738
rs1995398680233,772,448
rs20035690233,759,291
rs2818654180233,761,127
rs2818753790233,760,798
rs289348770233,768,333
rs30647440.9233,760,234
rs345476080233,760,182
rs348151090233,760,234
rs349469780233,768,226
rs349836510233,760,233
rs349937800233,772,413
rs350039770233,760,961
rs353509600233,760,973
rs356002880233,760,234
rs37553191233,758,936
rs3865766230233,768,333
rs41483230233,760,498
rs41483240233,764,076
rs41483250233,764,663
rs58394910234,668,885
rs5877767610233,767,046
rs5877767620233,760,800
rs5877767630233,760,761
rs5877767640233,761,152
rs5877767650233,760,432
rs5877767660233,768,218
rs5877845350233,767,937
rs626250110233,767,092
rs67175460233,773,473
rs67420782.1233,763,993
rs725513410233,760,811
rs725513483233,767,161
rs725513490233,767,873
rs725513500233,767,921
rs725513510233,767,922
rs725513530233,768,259
rs7552185460233,767,936
rs7970460900233,760,525
rs7970460910233,761,009
rs81753470233,760,235
rs83300233,772,999
rs8860397710233,760,640
rs8878292233,759,924

The UGT1A1 gene is located on chromosome 2, and it encodes a protein that modifies hepatic bilirubin in order to allow it to be excreted. SNPs that reduce the activity of the UGT1A1 gene therefore tend to increase serum bilirubin levels.

One particular variation in the promoter region of this gene, known as the UGT1A1*28 variant, has attracted the majority of attention, including an FDA approved genetic test applicable to potential users of the drugs irinotecan and tranilast. There are 4 SNPs in dbSNP that describe the same exact variation. They are:


Normally, i.e. in the wild-type UGT1A1*1 allele, there are six (TA) repeats at the position of these variants. The UGT1A1 alleles named based on variations at this positions include:

  • UGT1A1*36: five (TA) repeats - leading to increased promoter activity
  • UGT1A1*1: six (TA) repeats (this is the normal allele)
  • UGT1A1*28: seven (TA) repeats - leading to decreased promoter activity
  • UGT1A1*37: eight (TA) repeats - leading to decreased promoter activity


Note that when direct-to-consumer DNA testing companies using DNA chips return genotype results for one of these SNPs in the form of "II", "DI", or "DD", it can be ambiguous as to how many TA repeats the "I" and "D" designations correspond to.