Erythrocyte delta-aminolevulinic acid dehydratase genotype and other mechanisms affecting workers' susceptibility to lead

In this study the role of delta-aminolevulinic acid dehydratase (ALAD) vari ants in lead susceptibility was examined. The study subjects comprised 223 male workers, and the relationship between their blood lead level and eryth rocyte ALAD activity or plasma/urine delta-aminole-vulinic acid level was s tudied. Leukocyte specimens from 11 workers, whose erythrocyte ALAD activit ies were as low res one-fifth that of the other normal workers, were subjec ted to analyses of their ALAD(1) and ALAD(2) a alleles. Further, the entire exon fragment of the ALAD gene was analyzed by polymerase chain reaction, and the reaction product was used as a ta target for direct DNA sequencing. Genomic DNA analysis revealed that all 11 workers had the ALAD(1-1) allele , whereas the entire ALAD gene analysis failed to indicate other variants, except for the Rsa I site. The depletion in erythrocyte ALAD activity was n ot found to be caused by the ALAD(2) allele.