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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) and disturbances in the heme biosynthetic pathway by lead exposure.


METHODS
The subjects were 192 male lead workers and 125 control subjects. Blood lead concentrations (Pb-B), plasma ALA concentrations (ALA-P), and ALAD genotypes were determined for all subjects. In lead workers, ALAD activity, 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 to be 0.087 in all subjects. No significant relationship was found between ALAD2 frequency and Pb-B levels in lead workers. ALAD1 homozygotes showed significantly higher levels of ZP and ALA-P in comparison with those of ALAD2 carriers at Pb-B levels more than 20 microg/dL and 40 microg/dL, respectively.


CONCLUSIONS
ALAD1 homozygotes might be more susceptible than ALAD2 carriers to disturbances in heme metabolism caused by lead exposure.