|(A;A)||3.5||incapable of detoxifying byproducts of certain drugs|
|(A;G)||3||(TPMT*3B) impaired drug metabolism|
rs1800460 is a SNP in the TPMT gene, potentially encoding a variant incapable of detoxifying byproducts of certain antineoplastic and immunosuppressant drugs. In general, individuals must have two nonfunctioning TPMT alleles for the toxicity to be pronounced.
The risk allele for this SNP is rs1800460(A), and when it is the only variation in the TPMT gene, it encodes the TPMT*3B allele. While still rare, it is more common in Caucasians (4.5% of all alleles) than in African-Americans (0.8%). Note that if the same allele also carries the rs1142345(G) SNP, the allele is actually a TPMT*3A allele (OMIM).
The medicine 6-Mercaptopurine is metabolized by TPMT. Individual differences in TPMT activity associated with this SNP are now used to determine appropriate dosage range and interval for treatment.
|Disease||Thiopurine methyltransferase deficiency not provided|
|CLNDBN||Thiopurine methyltransferase deficiency not provided|
|CLNSRC||OMIM Allelic Variant UniProtKB (protein)|
|CLNACC||RCV000013559.25, RCV000013561.18, RCV000309972.1,|
[PMID 17366837] Genetic studies of a cluster of acute lymphoblastic leukemia cases in Churchill County, Nevada.
[PMID 18547414] Genotyping panel for assessing response to cancer chemotherapy.
[PMID 18662289] Pharmacogenomic studies of the anticancer and immunosuppressive thiopurines mercaptopurine and azathioprine.
[PMID 18685564] Genetic polymorphism of inosine triphosphate pyrophosphatase is a determinant of mercaptopurine metabolism and toxicity during treatment for acute lymphoblastic leukemia.
[PMID 22385887] High prevalence of polymorphism and low activity of thiopurine methyltransferase in patients with inflammatory bowel disease.
[PMID 23133420] Pharmacogenomic Diversity among Brazilians: Influence of Ancestry, Self-Reported Color, and Geographical Origin.