A study on the ALAD gene polymorphisms associated with lead exposure

Abstract

δ-aminolevulinic acid dehydratase (ALAD) plays an important role in lead poisoning, and polymorphisms in this gene may affect the response of individuals to lead toxicity symptoms. This study was carried out to examine the effects of ALAD gene polymorphism (G177C) on blood lead levels (BLL) and hematological parameters. In all, 113 battery manufacturing unit workers and 102 occupationally unexposed controls from Hyderabad, A.P, India formed the study group. Genotypes for the ALAD G177C polymorphism were determined by Polymerase chain reaction and restriction fragment length digestion. BLL were determined by anode stripping voltammetry using ESA Model 3010B Lead analyzer. Complete blood picture was analyzed using ADVIA cell counter for each sample. The frequencies for ALAD1 and ALAD2 alleles were 0.98 and 0.01, respectively. ALAD 1-2 and ALAD 2-2 genotypes together were considered as a single group and compared with the ALAD 1-1 genotype group. BLL did not differ significantly among ALAD1-1, 1-2, and 2-2 genotypes; however, subjects from the ALAD 1-2/2-2 genotype group showed higher BLL concentrations of 80.51 μg/dL when compared with subjects from the ALAD 1-1 genotype group (50.4 μg/dL). Approximately 29.2% volunteers ( n = 33) from the occupationally exposed group had hemoglobin levels below 10.0 g/dL. There was no significant difference in total white cell count and platelet count between occupational and non-exposed lead-exposed groups. BLL of occupationally exposed individuals were significantly high compared with the unexposed group. ALAD G177C polymorphism along with BLL and assessment of hematological parameters may play an important role in evaluation and better understanding of the consequences of lead exposure.