A polymorphism in the delta-aminolevulinic acid dehydratase gene may modify the pharmacokinetics and toxicity of lead

Environ Health Perspect. 1995 Mar;103(3):248-53. doi: 10.1289/ehp.95103248.


Associations between the presence of a constitutional variant of delta-aminolevulinic acid dehydratase (ALAD-2) and lead concentrations in blood and bone, as well as between this allele and indices of kidney function, were investigated among 691 members of a construction trade union. The average blood lead level in this group was 7.78 micrograms/dl. No significant difference was observed in blood lead concentration in ALAD-2 carriers compared to those homozygous for the more common ALAD-1 allele (7.78 +/- 3.62 micrograms Pb/dl vs. 7.73 ( +/- 3.48 micrograms Pb/dl, respectively; p = 0.73). Bone lead was measured in a subset of 122 of the study subjects. Patella minus tibia lead concentrations for each individual averaged 3.35 +/- 11.99 micrograms Pb/g bone mineral in ALAD-1 homozygotes and 8.62 +/- 9.47 micrograms Pb/g bone mineral in ALAD-2 carriers (p = 0.06). Comparisons of blood urea nitrogen (BUN) and uric acid by genotype indicated elevated levels among ALAD-2 individuals (p = 0.03 and 0.07, respectively). In logistic regression models accounting for other variables potentially associated with BUN and uric acid levels, BUN was significantly associated with blood lead levels (p = 0.01). Associations of BUN and uric acid levels with ALAD-2 were of borderline statistical significance in these models (p = 0.06 and 0.07). Taken together, these results suggest that the ALAD-2 genotype may influence the pharmacokinetic distribution and chronic renal toxicity of lead, perhaps due to differential binding of lead to the variant protein.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Alleles
  • Base Sequence
  • Blood Urea Nitrogen
  • Bone and Bones / chemistry
  • Construction Materials*
  • Heterozygote
  • Homozygote
  • Humans
  • Lead / analysis*
  • Lead / blood
  • Lead / pharmacokinetics
  • Male
  • Middle Aged
  • Molecular Sequence Data
  • Occupational Exposure*
  • Polymerase Chain Reaction
  • Porphobilinogen Synthase / genetics*


  • Lead
  • Porphobilinogen Synthase