Table 1.
Assignment of likely UGT1A1 phenotypes based on genotypes
| Likely phenotype | Genotypes | Examples of diplotypes |
|---|---|---|
| Extensive metabolizer |
An individual carrying two referenceb function (*1)c and/or increased function alleles (*36). Alternatively identified by homozygosity for rs887829 C/C. |
*1/*1; *1/*36; *36/*36; rs887829 C/C |
| Intermediate metabolizer | An individual carrying one referenceb function (*1)c or increased function allele (*36) plus one decreased function allele (*6, *28, *37). Alternatively identified by heterozygosity for rs887829 C/T. | *1/*28; *1/*37; *36/*28; *36/*37; rs887829 C/T, *1/*6 |
| Poor metabolizer | An individual carrying two decreased function alleles (*6, *28, *37). Alternatively identified by homozygosity for rs887829 T/T (*80/*80) | *28/*28; *28/*37; *37/*37; rs887829 T/T (*80/*80), *6/*6 a |
a
Homozygosity for UGT1A1*6, which occurs almost exclusively in individuals of Asian descent, is associated with Gilbert's syndrome. However, at this time it is unclear if patients with this diplotype are at increased risk of severe atazanavir‐associated hyperbilirubinemia.
b
“Reference” function refers to the UGT1A1 alleles to which other alleles are compared.
c
The reference function *1 allele is fully functional and refers to the rs8175347 TA6 allele.