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Updated: May 24, 2026

Genotyping Single Nucleotide Polymorphisms in the Mitochondrial Genome by Pyrosequencing
Published on: February 10, 2023
Validation of a genotyping method for analysis of TPMT polymorphisms
Manuel Román1, Teresa Cabaleiro, Dolores Ochoa
1Clinical Pharmacology Service, Hospital Universitario de la Princesa, Instituto Teófilo Hernando, UAM, Instituto de Investigación Sanitaria Princesa (IP), Madrid, Spain.
Background:
Thiopurine methyltransferase (TPMT) catalyzes the methylation of thiopurine drugs such as azathioprine and 6-mercaptopurine. Several mutations in the TPMT gene correlate with low enzyme activity and adverse effects such as myelotoxicity. Hence, genotyping TPMT makes it possible to identify patients at high risk for drug toxicity.
Objective:
The aim of this study was to validate a TPMT genotyping method by comparing it with a conventional polymerase chain reaction (PCR) approach.
Methods:
LightSNiP is a real-time PCR method for the detection of TPMT*2, *3B, and *3C without a sequencing step. We evaluated the frequencies of 3 TPMT alleles in 111 white adult patients by comparing genotyping by LightSNiP with conventional PCR (sequencing).
Results:
No differences were observed between conventional genotyping with sequencing and LightSNiP for *2, *3B, and *3C, suggesting the validity of this method.
Conclusions:
Compared with the conventional PCR sequencing method, the data suggest that LightSNiP correctly detected the TPMT *2, *3B, and *3C in this select population.
Related Concept Videos
Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase
Pharmacogenetics of Drug Targets: β₂-Adrenergic Receptors, Apo E, Thymidylate Synthase
Single Nucleotide Polymorphisms-SNPs

