Relationship between delta-aminolevulinic acid dehydratase genotypes and heme precursors in lead workers

Background The objective of this study was to investigate the relationships between genotypes of delta-aminolevulinic acid (ALA) dehydratase (ALAD) an d disturbances in the heme biosynthetic pathway by lead exposure. Methods The subjects were 192 male lead workers and 125 control subjects. B lood lead concentrations (Pb-B), plasma ALA concentrations (ALA-P), and ALA D genotypes were determined for all subjects. In lead workers, ALAD activit y, ALA in urine (ALA-U), and erythrocyte zinc protoporphyrin (ZP) were also determined. Results The frequency of ALAD2 (minor type of ALAD allele) was calculated t o be 0.087 in all subjects. No significant relationship was found between A LAD2 frequency and Pb-B levels in lend workers. ALAD1 homozygotes showed si gnificantly higher levels of ZP and ALA-P in comparison with those of ALAD2 carriers at Pb-B levels more than 20 mu g/dL and 40 mu g/dL, respectively. Conclusion ALAD1 homozygotes might be more susceptible than ALAD2 carriers to disturbances in heme metabolism caused by lead exposure. Am. J. Ind. Med . 38:355-360, 2000. (C) 2000 Wiley-Liss, Inc.