title: Association of genetic variation in cystathionine-beta-synthase and arsenic metabolism.
abstract: Variation in individual susceptibility to arsenic-induced disease may be partially explained by genetic differences in arsenic metabolism. Mounting epidemiological evidence and in vitro studies suggest that methylated arsenic metabolites, particularly monomethylarsonic (MMA3), are more acutely toxic than inorganic arsenic; thus, MMA3 may be the primary toxic arsenic species. To test the role of genetic variation in arsenic metabolism, polymorphisms in genes involved in one-carbon metabolism [methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), cystathionine-beta-synthase (CBS), thymidylate synthase (TYMS), dihydrofolate reductase (DHFR), serine hydroxymethyltransferase 1 (SHMT1)] and glutathione biosynthesis [glutathione-S-transferase omega 1 (GSTO1)] were examined in an arsenic-exposed population to determine their influence in urinary arsenic metabolite patterns. In 142 subjects in Cordoba Province, Argentina, variant genotypes for CBS rs234709 and rs4920037 SNPs compared with wild-type homozygotes were associated with 24% and 26% increases, respectively, in the mean proportion of arsenic excreted as monomethylarsonic acid (%MMA). This difference is within the range of differences in %MMA seen between people with arsenic-related disease and those without such disease in other studies. Small inverse associations with CBS rs234709 and rs4920037 variants were also found for the mean levels of the proportion of arsenic excreted as dimethylarsinous acid (%DMA). No other genetic associations were found. These findings are the first to suggest that CBS polymorphisms may influence arsenic metabolism in humans and susceptibility to arsenic-related disease.
authors.affiliation: School of Public Health, 237A Hildebrand Hall, University of California, Berkeley, CA 94720-7356, USA.
authors.forename: Kristin E
authors.initials: KE
authors.lastname: Porter
authors.forename: Anamika
authors.initials: A
authors.lastname: Basu
authors.forename: Alan E
authors.initials: AE
authors.lastname: Hubbard
authors.forename: Michael N
authors.initials: MN
authors.lastname: Bates
authors.forename: David
authors.initials: D
authors.lastname: Kalman
authors.forename: Omar
authors.initials: O
authors.lastname: Rey
authors.forename: Allan
authors.initials: A
authors.lastname: Smith
authors.forename: Martyn T
authors.initials: MT
authors.lastname: Smith
authors.forename: Craig
authors.initials: C
authors.lastname: Steinmaus
authors.forename: Christine F
authors.initials: CF
authors.lastname: Skibola
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001151:Arsenic / Q000633:toxicity / Q000652:urine*; D001152:Arsenicals / Q000652:urine; D002101:Cacodylic Acid / Q000031:analogs & derivatives / Q000652:urine; D003541:Cystathionine beta-Synthase / Q000235:genetics*; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D014873:Water Pollutants / Q000633:toxicity / Q000652:urine*
chemical_list: D001152:Arsenicals; D014873:Water Pollutants; C472511:dimethylarsinous acid; D002101:Cacodylic Acid; D003541:Cystathionine beta-Synthase; C020300:monomethylarsonic acid; D001151:Arsenic