We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
Genotype–phenotype correlation for thiopurine S-methyltransferase in healthy Italian subjects.
- Authors
Rossi, A. M.; Bianchi, M.; Guarnieri, C.; Barale, R.; Pacifici, G. M.
- Abstract
Objective: The aim of the present study was to estimate the concordance rate between erythrocyte thiopurine methyltransferase (TPMT) activity and genotype at the TPMT locus in an Italian population sample. Methods: The TPMT phenotype and genotype were determined in an unrelated population of 103 Italian healthy blood donors. Erythrocyte TPMT activity was measured with a radiochemical assay using 12.5 µM S-adenosyl-L-(methyl-14C)-methionine and 4 mM 6-mercaptopurine. The genotyping assay was based on restriction fragment length polymorphism polymerase chain reaction (RFLP-PCR) and allele-specific oligonucleotide polymerase chain reaction (ASO-PCR) methods. Results: All subjects had detectable TPMT activity. The activity of TPMT varied 2.8-fold between the 5th and 95th percentile. This variation was neither age (P=0.63) nor gender (P=0.44) regulated and the frequency distribution of TPMT activity is compatible with a polymorphic distribution. The presence of the four most common defective alleles, i.e. TPMT*2, TPMT*3A, TPMT*3B and TPMT*3C, was examined through the entire phenotyped population. Ninety-two subjects did not carry any of the tested mutations. Eleven individuals were heterozygous for one of the mutant alleles and had a TPMT activity lower than 30 pmol/min/mg. Eight subjects were TPMT*1/TPMT*3A, two TPMT*1/TPMT*3C and one was TPMT*1/TPMT*2. The TPMT*3B allele was not detected in the samples analysed. Conclusion: There was a concordance of 97% between genotype and phenotype. All the heterozygotes had an intermediate phenotype. However, the wide variation range in TPMT activity detected in the wild-type homozygotes indicates that other genetic or epigenetic factors influence the TPMT phenotype.
- Subjects
METHYLTRANSFERASES; PURINES; PHENOTYPES; GENOTYPE-environment interaction; HUMAN population genetics; ITALIANS
- Publication
European Journal of Clinical Pharmacology, 2001, Vol 57, Issue 1, p51
- ISSN
0031-6970
- Publication type
Article
- DOI
10.1007/s002280000246