Analysis of point mutations in HPRT mutant T-lymphocytes derived from coke-oven workers

We studied mutations in exon 3 of the hypoxanthine-guanine phosphoribosyltr ansferase (HPRT) locus in 113 6-thioguanine-resistant T-cell clones derived from coke-oven workers and control subjects in order to analyse possible c hanges in the mutational spectrum associated with the exposure to polycycli c aromatic hydrocarbons (PAHs). In 99 mutants, HPRT exon 3 was analysed by means of genomic polymerase chain reaction (PCR) and single-strand conforma tion polymorphism (SSCP). Products for which SSCP indicated the presence of a mutation were further analysed by DNA sequencing. In addition, HPRT cDNA from 14 clones was analysed by reverse transcription (RT) PCR and DNA sequ encing. In total, 18/113 mutants (16 %) had a mutation in exon 3. This freq uency was similar in PAM-exposed (9/57) and non-exposed (9/56) subjects. Ba se substitutions caused 14 mutations at 13 different sites. Three +/- bp fr ameshifts and one 6 bp deletion were identified. No significant differences between PAM-exposed and non-exposed workers were observed in this limited mutational spectrum. These results indicate that deletions/insertions at th e HPRT exon 3 account for 22% of the mutations. and base substitutions for 78%. (C) 1999 Elsevier Science B.V. All rights reserved.