A multiplex real-time PCR method for detection of GSTM1 and GSTT1 copy numbers

Clin Biochem. 2009 Apr;42(6):500-9. doi: 10.1016/j.clinbiochem.2008.12.011. Epub 2008 Dec 30.


Objectives: Deletion polymorphisms of Glutathione-S-transferase (GST) M1 and T1 are considered risk factors for various diseases. However, most previous studies only distinguished "null" and "non-null" genotypes. Our aim was to develop a reliable, high-throughput GSTM1/T1 genotyping method able to determine allele copy numbers.

Design and methods: We developed a multiplex real time PCR method to distinguish between heterozygous (1/0) and homozygous (1/1) GSTM1 and GSTT1 genotypes. The principle of relative quantification was applied and an expectation-maximisation (EM) algorithm was developed to assign one of 3 possible genotypes: 1/1, 1/0 or 0/0 for each of the two genes.

Results: 1320 Caucasians were genotyped using the newly developed method. The observed genotype distributions did not deviate from the expected and were in Hardy-Weinberg equilibrium. GSTM1 duplication was detected in one sample.

Conclusion: This new semiquantitative genotyping method is a sensitive and promising tool for large-scale molecular epidemiological and clinical studies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Blotting, Southern
  • DNA / analysis*
  • Gene Deletion
  • Gene Dosage*
  • Gene Duplication
  • Gene Frequency
  • Genetic Testing / methods
  • Glutathione Transferase / analysis
  • Glutathione Transferase / genetics*
  • Humans
  • Polymorphism, Genetic
  • Reverse Transcriptase Polymerase Chain Reaction / methods*
  • Sensitivity and Specificity


  • DNA
  • glutathione S-transferase T1
  • Glutathione Transferase
  • glutathione S-transferase M1