title: Association between aminolevulinate dehydrase genotypes and blood lead levels in children from a lead-contaminated area in Antofagasta, Chile.
abstract: Childhood environmental lead exposure in the city of Antofagasta, Chile, was generated by the accumulation of recently removed lead stores derived from mining activities for a long period of time. Susceptibility to harmful lead effects may be associated with polymorphisms of delta-aminolevulinic acid dehydratase (ALAD) because of the differential binding of lead to the codified proteins. We assessed the associations and possible interactions among the following variables: blood lead levels, ALAD genotypes, and distance to the source of lead contamination in Chilean children exposed to lead contamination in Antofagasta, Chile. Ninety-three children were recruited from schools located near a lead- contaminated area. Lead blood levels were measured by atomic absorption spectrophotometry. ALAD genotypes were determined by polymerase chain reaction and restriction fragment-length polymorphism analysis. The frequency of the ALAD-2 allele was estimated at 0.054. Children with the ALAD-2 genotype had higher blood lead levels than noncarriers (p = 0.06). As expected, blood lead levels were inversely correlated with the distance from lead stores. Interestingly, ALAD-2 carriers were more frequent within the area defined by a distance of 200 m from lead deposits (27%) than in areas >200 m (5%) away. Children living within a maximum distance of 200 m from the lead stores showed higher blood lead levels in ALAD-2 carriers (geometric mean = 16.4 microg/dl, range 6 to 27) than in noncarriers (geometric mean = 12.1 microg/dl, range 0 to 26) without achieving statistical significance (p = 0.13). A trend for higher blood lead levels in ALAD-2 carriers compared with ALAD-1 homozygous children has been observed. Because ALAD-2 frequency was higher in subjects living within 200 m from the lead deposits, we hypothesized that a long-term selective pressure against the presence of the ALAD-1 allele is the cause of the overrepresentation of the ALAD-2 allele in children living in proximity to the recently removed lead stores.
authors.affiliation: Unidad de Nutrición Pública, Programa de Epidemiologia Genética, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, PO Box 138-11, Santiago, Chile. fperez@uec.inta.uchile.cl
authors.forename: F
authors.initials: F
authors.lastname: Pérez-Bravo
authors.forename: M
authors.initials: M
authors.lastname: Ruz
authors.forename: M J
authors.initials: MJ
authors.lastname: Morán-Jiménez
authors.forename: M
authors.initials: M
authors.lastname: Olivares
authors.forename: A
authors.initials: A
authors.lastname: Rebolledo
authors.forename: J
authors.initials: J
authors.lastname: Codoceo
authors.forename: V
authors.initials: V
authors.lastname: Sepúlveda
authors.forename: A
authors.initials: A
authors.lastname: Jenkin
authors.forename: J L
authors.initials: JL
authors.lastname: Santos
authors.forename: A
authors.initials: A
authors.lastname: Fontanellas
mesh_terms: D002648:Child; D002669:Child Welfare; D002675:Child, Preschool; D002677:Chile; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000097:blood*; D005260:Female; D005838:Genotype; D006801:Humans; D007854:Lead / Q000097:blood*; D007855:Lead Poisoning / Q000209:etiology*; D008297:Male; D008906:Mining; D000623:Porphobilinogen Synthase / Q000235:genetics*; D012574:Schools
chemical_list: D004785:Environmental Pollutants; D007854:Lead; D000623:Porphobilinogen Synthase