Genetic factors modulate lead concentrations in the organism

Abstract

Lead (Pb) is a highly toxic heavy metal, even at low concentrations. There is no threshold considering "safe" for lead exposure. The toxic effects are due mainly to the enzymatic changes, such as inhibition of the enzyme delta aminolevulinic dehydratase (ALAD) and the ability to compete with calcium. The primary sites for lead absorption are gastrointestinal and respiratory tract. Once absorbed, lead is found in blood, soft tissues and mineralizing systems. Approximately 99% of the total body burden of lead is found in bones, body's major storage site. Around 1% of lead in blood is in plasma, representing the labile and biologically active lead fraction, able to pass the cells membranes and cause toxic effects. Despite the measures taken to reduce the concentrations of metal in nature, some individuals may be more susceptible to adverse effects caused by exposure to lead. Genetic factors has been studied and associated to differences among blood and plasma lead concentrations in subjects exposure. Subjects with different genotypes has proved lower or higher blood concentrations and plasma Pb. Recognize the individual or group of individuals more susceptible to high concentrations of lead can be a useful tool in preventing the toxic effects of metal. The gene coding for ALAD gene and of the Vitamin D Receptor (VDR), which are related to the toxicokinetics of lead have been outbreaks of this review.