Abstract
Matrix γ-carboxy glutamic acid protein (MGP) is a 10-kDa secreted protein containing five residues of the vitamin K-dependent calcium binding amino acid γ-carboxyglutamic acid (Gla). This study was carried out to examine the effects of MGP gene promoter polymorphism (T-138C) on blood lead levels (BLL) and hematological parameters in 113 battery manufacturing unit workers occupationally exposed to lead and 102 controls. Genotypes for the MGP T-138C polymorphism were determined by PCR and restriction fragment length digestion. BLL were determined by Anode Stripping Voltammetry using ESA Model 3010B Lead analyzer. Complete blood picture (CBP) was analyzed using ADVIA Cell counter for each sample. The frequencies of MGP–TT, CT and CC genotypes in our population were 38.6%, 44.3%, and 17.2%, respectively. The frequencies for T and C alleles were 0.612 and 0.386, respectively. Although BLL did not differ significantly among genotypes; they were higher in workers with TT/CT genotype compared to CC genotype subjects (76–88 μg/dL vs 22–45 μg/dL, p > 0.05). About 29.2% of volunteers (n = 33) from the occupationally exposed group had hemoglobin levels below 10.0 gms/dl. There was no significant difference in total white cell count and platelet count between occupational and non-exposed groups. The possible role of SNPs in the promoter region of MGP gene with relation to lead toxicity was investigated for the first time in the Indian population; although significance could not be achieved in this study, further assessments over a larger population size may help in better understanding of the consequences of lead exposure.
Highlights
Blood samples collected from all volunteers were analyzed for Complete blood picture (CBP) and only the parameters related to anemic conditions like hemoglobin are presented here
This study aims to identify the relation of some SNPs with emphasis on lead toxicity
Since Matrix γ-carboxy glutamic acid protein (MGP) gene is an important biomarker associated with atherosclerotic calcification and involved in calcium metabolism; it can be hypothesized that it may be associated with lead toxicity
Summary
Human MGP gene is located at 12p13.1–p12.3 and consists of four exons which codes for a 10-kDa Matrix Gla ( -carboxyglutamic acid) protein, containing five residues of the vitamin K-dependent calcium binding amino acid -carboxyglutamic acid (Gla). (Price et al 1983, 2000; Price and Williamson 1985; Shanahan et al 1998; Afshin et al 2001). Human MGP gene is located at 12p13.1–p12.3 and consists of four exons which codes for a 10-kDa Matrix Gla ( -carboxyglutamic acid) protein, containing five residues of the vitamin K-dependent calcium binding amino acid -carboxyglutamic acid (Gla). The accumulation of MGP protein in mineralized bone and calcified cartilage could be due to its calcium binding properties related to the presence of carboxylated residues and greatly exceeds that of the soft tissues, which fail to accumulate MGP under normal conditions but can do so when subjected to abnormal mineralization (Price et al 2000; Afshin et al 2001). Each exon of MGP corresponds to the domains found in all known vitamin K dependent vertebrate proteins: a transmembrane signal peptide, followed by putative gamma-carboxylation recognition site, and a Gla-containing domain (Luo et al 1997; Afshin et al 2001).
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